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Condens. Matter, Volume 4, Issue 1 (March 2019)

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Open AccessReview Evolution of Complexity in Out-of-Equilibrium Systems by Time-Resolved or Space-Resolved Synchrotron Radiation Techniques
Condens. Matter 2019, 4(1), 32; https://doi.org/10.3390/condmat4010032
Received: 23 February 2019 / Revised: 11 March 2019 / Accepted: 13 March 2019 / Published: 14 March 2019
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Abstract
Out-of-equilibrium phenomena are attracting high interest in physics, materials science, chemistry and life sciences. In this state, the study of structural fluctuations at different length scales in time and space are necessary to achieve significant advances in the understanding of the structure-functionality relationship. [...] Read more.
Out-of-equilibrium phenomena are attracting high interest in physics, materials science, chemistry and life sciences. In this state, the study of structural fluctuations at different length scales in time and space are necessary to achieve significant advances in the understanding of the structure-functionality relationship. The visualization of patterns arising from spatiotemporal fluctuations is nowadays possible thanks to new advances in X-ray instrumentation development that combine high-resolution both in space and in time. We present novel experimental approaches using high brilliance synchrotron radiation sources, fast detectors and focusing optics, joint with advanced data analysis based on automated statistical, mathematical and imaging processing tools. This approach has been used to investigate structural fluctuations in out-of-equilibrium systems in the novel field of inhomogeneous quantum complex matter at the crossing point of technology, physics and biology. In particular, we discuss how nanoscale complexity controls the emergence of high-temperature superconductivity (HTS), myelin functionality and formation of hybrid organic-inorganic supramolecular assembly. The emergent complex geometries, opening novel venues to quantum technology and to the development of quantum physics of living systems, are discussed. Full article
Open AccessArticle Energy Response of Silicon Drift Detectors for Kaonic Atom Precision Measurements
Condens. Matter 2019, 4(1), 31; https://doi.org/10.3390/condmat4010031
Received: 29 January 2019 / Revised: 1 March 2019 / Accepted: 6 March 2019 / Published: 11 March 2019
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Abstract
Novel, large-area silicon drift detectors (SDDs) have been developed to perform precision measurements of kaonic atom X-ray spectroscopy, for the study the K¯N strong interaction in the low-energy regime. These devices have special geometries, field configurations and read-out electronics, resulting in [...] Read more.
Novel, large-area silicon drift detectors (SDDs) have been developed to perform precision measurements of kaonic atom X-ray spectroscopy, for the study the K ¯ N strong interaction in the low-energy regime. These devices have special geometries, field configurations and read-out electronics, resulting in excellent performances in terms of linearity, stability and energy resolution. In this work the SDDs energy response in the energy region between 4000 eV and 12,000 eV is reported, revealing a stable linear response within 1 eV and good energy resolution. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle The Potential of [email protected]_LAB for Radiation Based Techniques
Condens. Matter 2019, 4(1), 30; https://doi.org/10.3390/condmat4010030
Received: 31 January 2019 / Revised: 1 March 2019 / Accepted: 2 March 2019 / Published: 7 March 2019
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Abstract
A proposal for building a Free Electron Laser, [email protected]_LAB, at the Laboratori Nazionali di Frascati, is at present under consideration. This FEL facility will provide a unique combination of a high brightness GeV-range electron beam generated in a X-band RF linac, a 0.5 [...] Read more.
A proposal for building a Free Electron Laser, [email protected]_LAB, at the Laboratori Nazionali di Frascati, is at present under consideration. This FEL facility will provide a unique combination of a high brightness GeV-range electron beam generated in a X-band RF linac, a 0.5 PW-class laser system and the first FEL source driven by a plasma accelerator. The FEL will produce ultra-bright pulses, with up to 10 12 photons/pulse, femtosecond timescale and wavelength down to 3 nm, which lies in the so called “water window”. The experimental activity will be focused on the realization of a plasma driven short wavelength FEL able to provide high-quality photons for a user beamline. In this paper, we describe the main classes of experiments that will be performed at the facility, including coherent diffraction imaging, soft X-ray absorption spectroscopy, Raman spectroscopy, Resonant Inelastic X-ray Scattering and photofragmentation measurements. These techniques will allow studying a variety of samples, both biological and inorganic, providing information about their structure and dynamical behavior. In this context, the possibility of inducing changes in samples via pump pulses leading to the stimulation of chemical reactions or the generation of coherent excitations would tremendously benefit from pulses in the soft X-ray region. High power synchronized optical lasers and a TeraHertz radiation source will indeed be made available for THz and pump–probe experiments and a split-and-delay station will allow performing XUV-XUV pump–probe experiments. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle Impact of Surface Roughness on Ion-Surface Interactions Studied with Energetic Carbon Ions 13C+ on Tungsten Surfaces
Condens. Matter 2019, 4(1), 29; https://doi.org/10.3390/condmat4010029
Received: 12 January 2019 / Revised: 23 February 2019 / Accepted: 25 February 2019 / Published: 5 March 2019
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Abstract
The effect of surface roughness on angular distributions of reflected and physically sputtered particles is investigated by ultra-high vacuum (UHV) ion-surface interaction experiments. For this purpose, a smooth (Ra = 5.9 nm) and a rough (Ra = 20.5 nm) [...] Read more.
The effect of surface roughness on angular distributions of reflected and physically sputtered particles is investigated by ultra-high vacuum (UHV) ion-surface interaction experiments. For this purpose, a smooth (Ra = 5.9 nm) and a rough (Ra = 20.5 nm) tungsten (W) surface were bombarded with carbon ions 13C+ under incidence angles of 30° and 80°. Reflected and sputtered particles were collected on foils to measure the resulting angular distribution as a function of surface morphology. For the qualitative and quantitative analysis, secondary ion mass spectrometry (SIMS) and nuclear reaction analysis (NRA) were performed. Simulations of ion-surface interactions were carried out with the SDTrimSP (Static Dynamic Transport of Ions in Matter Sputtering) code. For rough surfaces, a special routine was derived and implemented. Experimental as well as calculated results prove a significant impact of surface roughness on the angular distribution of reflected and sputtered particles. It is demonstrated that the effective sticking of C on W is a function of the angle of incidence and surface morphology. It is found that the predominant ion-surface interaction process changes with fluence. Full article
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Open AccessArticle Electronic Structure of Boron Flat Holeless Sheet
Condens. Matter 2019, 4(1), 28; https://doi.org/10.3390/condmat4010028
Received: 30 January 2019 / Revised: 20 February 2019 / Accepted: 26 February 2019 / Published: 3 March 2019
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Abstract
The electronic band structure, namely energy band surfaces and densities-of-states (DoS), of a hypothetical flat and ideally perfect, i.e., without any type of holes, boron sheet with a triangular network is calculated within a quasi-classical approach. It is shown to have metallic properties [...] Read more.
The electronic band structure, namely energy band surfaces and densities-of-states (DoS), of a hypothetical flat and ideally perfect, i.e., without any type of holes, boron sheet with a triangular network is calculated within a quasi-classical approach. It is shown to have metallic properties as is expected for most of the possible structural modifications of boron sheets. The Fermi curve of the boron flat sheet is found to be consisted of 6 parts of 3 closed curves, which can be approximated by ellipses representing the quadric energy-dispersion of the conduction electrons. The effective mass of electrons at the Fermi level in a boron flat sheet is found to be too small compared with the free electron mass m 0 and to be highly anisotropic. Its values distinctly differ in directions Γ–K and Γ–M: m Γ K / m 0 0.480 and m Γ M / m 0 0.052 , respectively. The low effective mass of conduction electrons, m σ / m 0 0.094 , indicates their high mobility and, hence, high conductivity of the boron sheet. The effects of buckling/puckering and the presence of hexagonal or other type of holes expected in real boron sheets can be considered as perturbations of the obtained electronic structure and theoretically taken into account as effects of higher order. Full article
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Open AccessArticle Experimental Observation of Temperature-Driven Topological Phase Transition in HgTe/CdHgTe Quantum Wells
Condens. Matter 2019, 4(1), 27; https://doi.org/10.3390/condmat4010027
Received: 28 January 2019 / Revised: 23 February 2019 / Accepted: 28 February 2019 / Published: 1 March 2019
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Abstract
We report on the comparison between temperature-dependent magneto-absorption and magnetotransport spectroscopy of HgTe/CdHgTe quantum wells in terms of the detection of the phase transition between the topological insulator and band insulator states. Our results demonstrate that temperature-dependent magnetospectroscopy is a powerful tool to [...] Read more.
We report on the comparison between temperature-dependent magneto-absorption and magnetotransport spectroscopy of HgTe/CdHgTe quantum wells in terms of the detection of the phase transition between the topological insulator and band insulator states. Our results demonstrate that temperature-dependent magnetospectroscopy is a powerful tool to discriminate trivial and topological insulator phases, yet the magnetotransport method is shown to have advantages for the clear manifestation of the phase transition with accurate quantitative values of the transition parameter (i.e., critical magnetic field Bc). Full article
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Open AccessArticle Model of Nano-Metal Electroplating Process in Trapezoid Profile Groove
Condens. Matter 2019, 4(1), 26; https://doi.org/10.3390/condmat4010026
Received: 26 December 2018 / Revised: 11 February 2019 / Accepted: 19 February 2019 / Published: 21 February 2019
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Abstract
The principle of the electrodeposition method is to immerse the coated products in a water electrolyte solution, the main components of which are salts or other soluble compounds—metal coatings. The software COMSOL Multiphysics was allowed to perform a simulation of the processes of [...] Read more.
The principle of the electrodeposition method is to immerse the coated products in a water electrolyte solution, the main components of which are salts or other soluble compounds—metal coatings. The software COMSOL Multiphysics was allowed to perform a simulation of the processes of electrodeposition of the metals copper and silver in the groove of the trapezoidal profile. Full article
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Open AccessArticle Engineering Topological Nodal Line Semimetals in Rashba Spin-Orbit Coupled Atomic Chains
Condens. Matter 2019, 4(1), 25; https://doi.org/10.3390/condmat4010025
Received: 30 January 2019 / Revised: 13 February 2019 / Accepted: 15 February 2019 / Published: 16 February 2019
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Abstract
In this paper, we study an atomic chain in the presence of modulated charge potential and modulated Rashba spin-orbit coupling (RSOC) of equal periods. We show that for commensurate periodicities, λ=4n with integer n, the three-dimensional synthetic space obtained [...] Read more.
In this paper, we study an atomic chain in the presence of modulated charge potential and modulated Rashba spin-orbit coupling (RSOC) of equal periods. We show that for commensurate periodicities, λ = 4 n with integer n, the three-dimensional synthetic space obtained by sliding the two phases of the charge potential and RSOC features a topological nodal-line semimetal protected by an anti-unitary particle-hole symmetry. The location and shape of the nodal lines strongly depend on the relative amplitude between the charge potential and RSOC. Full article
(This article belongs to the Special Issue Majorana Fermions and Topological Materials Science)
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Open AccessArticle Scintillator Pixel Detectors for Measurement of Compton Scattering
Condens. Matter 2019, 4(1), 24; https://doi.org/10.3390/condmat4010024
Received: 31 January 2019 / Revised: 12 February 2019 / Accepted: 13 February 2019 / Published: 15 February 2019
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Abstract
The Compton scattering of gamma rays is commonly detected using two detector layers, the first for detection of the recoil electron and the second for the scattered gamma. We have assembled detector modules consisting of scintillation pixels, which are able to detect and [...] Read more.
The Compton scattering of gamma rays is commonly detected using two detector layers, the first for detection of the recoil electron and the second for the scattered gamma. We have assembled detector modules consisting of scintillation pixels, which are able to detect and reconstruct the Compton scattering of gammas with only one readout layer. This substantially reduces the number of electronic channels and opens the possibility to construct cost-efficient Compton scattering detectors for various applications such as medical imaging, environment monitoring, or fundamental research. A module consists of a 4 × 4 matrix of lutetium fine silicate scintillators and is read out by a matching silicon photomultiplier array. Two modules have been tested with a 22 Na source in coincidence mode, and the performance in the detection of 511 keV gamma Compton scattering has been evaluated. The results show that Compton events can be clearly distinguished with a mean energy resolution of 12.2% ± 0.7% in a module and a coincidence time resolution of 0.56 ± 0.02 ns between the two modules. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle Temperature Effects on the HOPG Intercalation Process
Condens. Matter 2019, 4(1), 23; https://doi.org/10.3390/condmat4010023
Received: 15 December 2018 / Revised: 4 February 2019 / Accepted: 10 February 2019 / Published: 14 February 2019
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Abstract
Graphite intercalation via chemical strategies is a common procedure to delaminate stratified crystals and obtain a suspension of graphene flakes. The intercalation mechanism at the molecular level is still under investigation in view of enhancing graphene production and reducing damage to the original [...] Read more.
Graphite intercalation via chemical strategies is a common procedure to delaminate stratified crystals and obtain a suspension of graphene flakes. The intercalation mechanism at the molecular level is still under investigation in view of enhancing graphene production and reducing damage to the original pristine crystal. The latter, in particular, can undergo surface detriment due to both blister evolution and carbon dissolution. The role of the electrolyte temperature in this process has never been investigated. Here, by using an in-situ atomic force microscopy (AFM) apparatus, we explore surface morphology changes after the application of fast cyclic-voltammetries at 343 K, in view of de-coupling the crystal swelling phenomenon from the other electrochemical processes. We find that blisters do not evolve as a consequence of the increasing temperature, while the quality of the graphite surface becomes significantly worse, due to the formation of some adsorbates on possible defect sites of the electrode surface. Our results suggest that the chemical baths used in graphite delamination must be carefully monitored in temperature for avoiding undesired electrode detriment. Full article
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Open AccessReview The Variational Reduction for Low-Dimensional Fermi Gases and Bose–Fermi Mixtures: A Brief Review
Condens. Matter 2019, 4(1), 22; https://doi.org/10.3390/condmat4010022
Received: 26 December 2018 / Revised: 24 January 2019 / Accepted: 5 February 2019 / Published: 10 February 2019
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Abstract
We present a summary of some recent theoretical results for matter-wave patterns in Fermi and Bose–Fermi degenerate gases, obtained in the framework of the quasi-mean-field approximation. We perform a dimensional reduction from the three-dimensional (3D) equations of motion to 2D and 1D effective [...] Read more.
We present a summary of some recent theoretical results for matter-wave patterns in Fermi and Bose–Fermi degenerate gases, obtained in the framework of the quasi-mean-field approximation. We perform a dimensional reduction from the three-dimensional (3D) equations of motion to 2D and 1D effective equations. In both cases, comparison of the low-dimensional reductions to the full model is performed, showing very good agreement for ground-state solutions. Some complex dynamical regimes are reported too for the corresponding 1D systems. Full article
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Open AccessArticle Effect of High-Temperature Annealing on Graphene with Nickel Contacts
Condens. Matter 2019, 4(1), 21; https://doi.org/10.3390/condmat4010021
Received: 9 January 2019 / Revised: 1 February 2019 / Accepted: 1 February 2019 / Published: 6 February 2019
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Abstract
Graphene has shown great potential for ultra-high frequency electronics. However, using graphene in electronic devices creates a requirement for electrodes with low contact resistance. Thermal annealing is sometimes used to improve the performance of contact electrodes. However, high-temperature annealing may introduce additional doping [...] Read more.
Graphene has shown great potential for ultra-high frequency electronics. However, using graphene in electronic devices creates a requirement for electrodes with low contact resistance. Thermal annealing is sometimes used to improve the performance of contact electrodes. However, high-temperature annealing may introduce additional doping or defects to graphene. Moreover, an extensive increase in temperature may damage electrodes by destroying the metal–graphene contact. In this work, we studied the effect of high-temperature annealing on graphene and nickel–graphene contacts. Annealing was done in the temperature range of 200–800 °C and the effect of the annealing temperature was observed by two and four-point probe resistance measurements and by Raman spectroscopy. We observed that the annealing of a graphene sample above 300 °C increased the level of doping, but did not always improve electrical contacts. Above 600 °C, the nickel–graphene contact started to degrade, while graphene survived even higher process temperatures. Full article
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Open AccessArticle Zero-Temperature Equation of State of a Two-Dimensional Bosonic Quantum Fluid with Finite-Range Interaction
Condens. Matter 2019, 4(1), 20; https://doi.org/10.3390/condmat4010020
Received: 20 January 2019 / Revised: 30 January 2019 / Accepted: 30 January 2019 / Published: 3 February 2019
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Abstract
We derive the two-dimensional equation of state for a bosonic system of ultracold atoms interacting with a finite-range effective interaction. Within a functional integration approach, we employ a hydrodynamic parameterization of the bosonic field to calculate the superfluid equations of motion and the [...] Read more.
We derive the two-dimensional equation of state for a bosonic system of ultracold atoms interacting with a finite-range effective interaction. Within a functional integration approach, we employ a hydrodynamic parameterization of the bosonic field to calculate the superfluid equations of motion and the zero-temperature pressure. The ultraviolet divergences, naturally arising from the finite-range interaction, are regularized with an improved dimensional regularization technique. Full article
Open AccessBrief Report Simulation of the Process of Obtaining Nanoparticles by Thermal Decomposition
Condens. Matter 2019, 4(1), 19; https://doi.org/10.3390/condmat4010019
Received: 26 December 2018 / Revised: 21 January 2019 / Accepted: 26 January 2019 / Published: 29 January 2019
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Abstract
In this work, the possibility of modeling the process of thermal decomposition in the COMSOL Multiphysics program for the preparation of nanoparticles of metals and their alloys was determined. To identify the most suitable pyrolysis medium, two environments are presented: a water solution [...] Read more.
In this work, the possibility of modeling the process of thermal decomposition in the COMSOL Multiphysics program for the preparation of nanoparticles of metals and their alloys was determined. To identify the most suitable pyrolysis medium, two environments are presented: a water solution and ethanol. Full article
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Open AccessArticle Graphite Optics—Current Opportunities, Properties and Limits
Condens. Matter 2019, 4(1), 18; https://doi.org/10.3390/condmat4010018
Received: 21 November 2018 / Revised: 11 January 2019 / Accepted: 21 January 2019 / Published: 24 January 2019
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Abstract
X-ray graphite optics consists of thin layers of Pyrolytic Graphite (PG) attached to a substrate of focusing shape. Pyrolytic Graphite is a perfect artificial graphite obtained by annealing of carbon deposit at temperatures about 3000 °C under deformation. By varying the annealing conditions, [...] Read more.
X-ray graphite optics consists of thin layers of Pyrolytic Graphite (PG) attached to a substrate of focusing shape. Pyrolytic Graphite is a perfect artificial graphite obtained by annealing of carbon deposit at temperatures about 3000 °C under deformation. By varying the annealing conditions, one could get PG of different mosaic structure and mechanical properties. A wide variability of the reflecting layer characteristics and optics shape makes the graphite optics useful in an extended range of applications. The optics could be adjusted to applications that require moderate resolution as EDXRF (energy dispersive X-Ray fluorescence) and as well as for high-resolution applications as EXAFS (extended X-ray absorption fine structure), XANES (X-ray absorption near-edge structure) and XES (X-ray emission spectroscopy). To realize the optics with theoretically optimized parameters the relationship between the production procedure and the mosaicity and reflectivity of the optics was experimentally studied. The influence of thickness, the type of PG (Highly Oriented PG (HOPG) or Highly Annealed PG (HAPG)) and substrate characteristics on the optics performance is presented. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle Many-Body Physics of Low-Density Dipolar Bosons in Box Potentials
Condens. Matter 2019, 4(1), 17; https://doi.org/10.3390/condmat4010017
Received: 13 December 2018 / Revised: 16 January 2019 / Accepted: 19 January 2019 / Published: 22 January 2019
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Abstract
Crystallization is a generic phenomenon in classical and quantum mechanics arising in a variety of physical systems. In this work, we focus on a specific platform, ultracold dipolar bosons, which can be realized in experiments with dilute gases. We reviewed the relevant ingredients [...] Read more.
Crystallization is a generic phenomenon in classical and quantum mechanics arising in a variety of physical systems. In this work, we focus on a specific platform, ultracold dipolar bosons, which can be realized in experiments with dilute gases. We reviewed the relevant ingredients leading to crystallization, namely the interplay of contact and dipole–dipole interactions and system density, as well as the numerical algorithm employed. We characterized the many-body phases investigating correlations and superfluidity. Full article
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Open AccessEditorial Acknowledgement to Reviewers of Condensed Matter in 2018
Condens. Matter 2019, 4(1), 16; https://doi.org/10.3390/condmat4010016
Published: 21 January 2019
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Abstract
Peer review is an essential part in the publication process, ensuring that Condensed Matter maintains high quality standards for its published papers [...] Full article
Open AccessArticle Multiple Electronic Components and Lifshitz Transitions by Oxygen Wires Formation in Layered Cuprates and Nickelates
Condens. Matter 2019, 4(1), 15; https://doi.org/10.3390/condmat4010015
Received: 26 December 2018 / Revised: 16 January 2019 / Accepted: 16 January 2019 / Published: 21 January 2019
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Abstract
There is growing compelling experimental evidence that a quantum complex matter scenario made of multiple electronic components and competing quantum phases is needed to grab the key physics of high critical temperature (Tc) superconductivity in layered cuprates. While it is [...] Read more.
There is growing compelling experimental evidence that a quantum complex matter scenario made of multiple electronic components and competing quantum phases is needed to grab the key physics of high critical temperature (Tc) superconductivity in layered cuprates. While it is known that defect self-organization controls Tc, the mechanism remains an open issue. Here we focus on the theoretical prediction of the multiband electronic structure and the formation of broken Fermi surfaces generated by the self-organization of oxygen interstitials Oi atomic wires in the spacer layers in HgBa2CuO4+δ, La2CuO4+δ and La2NiO4+δ, by means of self-consistent Linear Muffin-Tin Orbital (LMTO) calculations. The electronic structure of a first phase of ordered Oi atomic wires and of a second glassy phase made of disordered Oi impurities have been studied through supercell calculations. We show the common features of the influence of Oi wires in the electronic structure in three types of materials. The ordering of Oi into wires leads to a separation of the electronic states between the Oi ensemble and the rest of the bulk. The wire formation first produces quantum confined localized states near the wire, which coexist with, Second, delocalized states in the Fermi surface (FS) of doped cuprates. A new scenario emerges for high Tc superconductivity, where Kitaev wires with Majorana bound states are proximity-coupled to a 2D d-wave superconductor. Full article
(This article belongs to the Special Issue From cuprates to Room Temperature Superconductors)
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Open AccessArticle A Novel Bulk-Optics Scheme for Quantum Walk with High Phase Stability
Condens. Matter 2019, 4(1), 14; https://doi.org/10.3390/condmat4010014
Received: 30 November 2018 / Revised: 6 January 2019 / Accepted: 17 January 2019 / Published: 18 January 2019
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Abstract
A novel bulk optics scheme for quantum walks is presented. It consists of a one-dimensional lattice built on two concatenated displaced Sagnac interferometers that make it possible to reproduce all the possible trajectories of an optical quantum walk. Because of the closed loop [...] Read more.
A novel bulk optics scheme for quantum walks is presented. It consists of a one-dimensional lattice built on two concatenated displaced Sagnac interferometers that make it possible to reproduce all the possible trajectories of an optical quantum walk. Because of the closed loop configuration, the interferometric structure is intrinsically stable in phase. Moreover, the lattice structure is highly configurable, as any phase component perceived by the walker is accessible, and finally, all output modes can be measured at any step of the quantum walk evolution. We report here on the experimental implementation of ordered and disordered quantum walks. Full article
(This article belongs to the Special Issue Quantum Cellular Automata and Quantum Walks)
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Open AccessArticle X-Ray Absorption Spectroscopy Measurements of Cu-ProIAPP Complexes at Physiological Concentrations
Condens. Matter 2019, 4(1), 13; https://doi.org/10.3390/condmat4010013
Received: 12 December 2018 / Revised: 11 January 2019 / Accepted: 15 January 2019 / Published: 18 January 2019
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Abstract
The amyloidogenic islet amyloid polypeptide (IAPP) and the associated pro-peptide ProIAPP1–48 are involved in cell death in type 2 diabetes mellitus. It has been observed that interactions of this peptide with metal ions have an impact on the cytotoxicity of the peptides [...] Read more.
The amyloidogenic islet amyloid polypeptide (IAPP) and the associated pro-peptide ProIAPP1–48 are involved in cell death in type 2 diabetes mellitus. It has been observed that interactions of this peptide with metal ions have an impact on the cytotoxicity of the peptides as well as on their deposition in the form of amyloid fibrils. In particular, Cu(II) seems to inhibit amyloid fibril formation, thus suggesting that Cu homeostasis imbalance may be involved in the pathogenesis of type 2 diabetes mellitus. We performed X-ray Absorption Spectroscopy (XAS) measurements of Cu(II)-ProIAPP complexes under near-physiological (10 μM), equimolar concentrations of Cu(II) and peptide. Such low concentrations were made accessible to XAS measurements owing to the use of the High Energy Resolved Fluorescence Detection XAS facility recently installed at the ESRF beamline BM16 (FAME-UHD). Our preliminary data show that XAS measurements at micromolar concentrations are feasible and confirm that ProIAPP1–48-Cu(II) binding at near-physiological conditions can be detected. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle The New Beamline LISA at ESRF: Performances and Perspectives for Earth and Environmental Sciences
Condens. Matter 2019, 4(1), 12; https://doi.org/10.3390/condmat4010012
Received: 29 November 2018 / Revised: 11 January 2019 / Accepted: 12 January 2019 / Published: 15 January 2019
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Abstract
LISA (Linea Italiana per la Spettroscopia di Assorbimento di raggi X) is the new Italian Collaborating Research Group (CRG) beamline at the European Synchrotron Radiation Facility (ESRF) dedicated to X-ray absorption spectroscopy (XAS). The beamline covers a wide energy range, 4 < E [...] Read more.
LISA (Linea Italiana per la Spettroscopia di Assorbimento di raggi X) is the new Italian Collaborating Research Group (CRG) beamline at the European Synchrotron Radiation Facility (ESRF) dedicated to X-ray absorption spectroscopy (XAS). The beamline covers a wide energy range, 4 < E < 90 keV, which offers the possibility for probe the K and L edges of elements that are heavier than Ca. A liquid He/N2 cryostat and a compact furnace are available for measurements in a wide temperature range (10–1000 K), allowing for in situ chemical treatments and measurements under a controlled atmosphere. The sub-millimetric beam size, the high photon flux provided, and the X-ray fluorescence detectors available (HP-Ge, SDD) allow for the study of liquid and highly diluted samples. Trace elements in geological or environmental samples can be analyzed, even for very small sample areas, gaining information on oxidation states and host phases. Full article
(This article belongs to the Special Issue Condensed Matter Researches in Cryospheric Science)
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Open AccessArticle Exchange Interactions and Curie Temperature of Ce-Substituted SmCo5
Condens. Matter 2019, 4(1), 11; https://doi.org/10.3390/condmat4010011
Received: 13 December 2018 / Revised: 7 January 2019 / Accepted: 8 January 2019 / Published: 14 January 2019
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A partial substitution such as Ce in SmCo5 could be a brilliant way to improve the magnetic performance, because it will introduce strain in the structure and breaks the lattice symmetry in a way that enhances the contribution of the Co atoms [...] Read more.
A partial substitution such as Ce in SmCo 5 could be a brilliant way to improve the magnetic performance, because it will introduce strain in the structure and breaks the lattice symmetry in a way that enhances the contribution of the Co atoms to magnetocrystalline anisotropy. However, Ce substitutions, which are benefit to improve the magnetocrystalline anisotropy, are detrimental to enhance the Curie temperature ( T C ). With the requirements of wide operating temperature range of magnetic devices, it is important to quantitatively explore the relationship between the T C and ferromagnetic exchange energy. In this paper we show, based on mean-field approximation, artificial tensile strain in SmCo 5 induced by substitution leads to enhanced effective ferromagnetic exchange energy and T C , even though Ce atom itself reduces T C . Full article
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Open AccessArticle Impact of Lattice Vibrations on the Dynamics of a Spinor Atom-Optics Kicked Rotor
Condens. Matter 2019, 4(1), 10; https://doi.org/10.3390/condmat4010010
Received: 27 December 2018 / Accepted: 8 January 2019 / Published: 14 January 2019
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We investigate the effect of amplitude and phase noise on the dynamics of a discrete-time quantum walk and its related evolution. Our findings underline the robustness of the motion with respect to these noise sources, and can explain the stability of quantum walks [...] Read more.
We investigate the effect of amplitude and phase noise on the dynamics of a discrete-time quantum walk and its related evolution. Our findings underline the robustness of the motion with respect to these noise sources, and can explain the stability of quantum walks that has recently been observed experimentally. This opens the road to measure topological properties of an atom-optics double kicked rotor with an additional internal spin degree of freedom. Full article
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Open AccessArticle Proximity-Induced Superconducting States of Magnetically Doped 3D Topological Insulators with High Bulk Insulation
Condens. Matter 2019, 4(1), 9; https://doi.org/10.3390/condmat4010009
Received: 25 November 2018 / Revised: 22 December 2018 / Accepted: 7 January 2019 / Published: 12 January 2019
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Abstract
We studied magnetized topological insulator/superconductor junctions with the expectation of unconventional superconductive states holding Majorana fermions induced by superconductive proximity effects on the surface states of magnetized topological insulators (TIs), attached by conventional superconductors. We introduced Fe-doped BiSbTe2Se as an ideal [...] Read more.
We studied magnetized topological insulator/superconductor junctions with the expectation of unconventional superconductive states holding Majorana fermions induced by superconductive proximity effects on the surface states of magnetized topological insulators (TIs), attached by conventional superconductors. We introduced Fe-doped BiSbTe2Se as an ideal magnetic TI and used the developed junction fabrication process to access the proximity-induced surface superconducting states. The bulk single crystals of the Fe-doped TI showed excellent bulk-insulating properties and ferromagnetism simultaneously at a low temperature. Meanwhile, the fabricated junctions also showed an insulating behavior above 100 K, as well as metallic conduction at a low temperature, which reflects bulk carrier freezing. In addition, we observed a proximity-induced gap structure in the conductance spectra. These results indicate that the junctions using the established materials and process are preferable to observe unconventional superconducting states which are induced via the surface channels of the magnetized TI. We believe that the developed process can be applied for the fabrication of complicated junctions and suites for braiding operations. Full article
(This article belongs to the Special Issue Majorana Fermions and Topological Materials Science)
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Open AccessArticle Polarization Analysis in Mössbauer Reflectometry with Synchrotron Mössbauer Source
Condens. Matter 2019, 4(1), 8; https://doi.org/10.3390/condmat4010008
Received: 1 October 2018 / Revised: 14 December 2018 / Accepted: 2 January 2019 / Published: 8 January 2019
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Abstract
Polarization selection of the reflected radiation has been employed in Mössbauer reflectivity measurements with a synchrotron Mössbauer source (SMS). The polarization of resonantly scattered radiation differs from the polarization of an incident wave so the Mössbauer reflectivity contains a scattering component with 90° [...] Read more.
Polarization selection of the reflected radiation has been employed in Mössbauer reflectivity measurements with a synchrotron Mössbauer source (SMS). The polarization of resonantly scattered radiation differs from the polarization of an incident wave so the Mössbauer reflectivity contains a scattering component with 90° rotated polarization relative to the π-polarization of the SMS for some hyperfine transitions. We have shown that the selection of this rotated π→σ component from total reflectivity gives an unusual angular dependence of reflectivity characterized by a peak near the critical angle of the total external reflection. In the case of collinear antiferromagnetic interlayer ordering, the “magnetic” maxima on the reflectivity angular curve are formed practically only by radiation with this rotated polarization. The first experiment on Mössbauer reflectivity with a selection of the rotated polarization discovers the predicted peak near the critical angle. The measurement of the rotated π→σ polarization component in Mössbauer reflectivity spectra excludes the interference with non-resonant electronic scattering and simplifies the spectrum shape near the critical angle allowing for an improved data interpretation in the case of poorly resolved spectra. It is shown that the selected component of Mössbauer reflectivity with rotated polarization is characterized by enhanced surface sensitivity, determined by the “squared standing waves” depth dependence. Therefore, the new approach has interesting perspectives for investigations of surfaces, ultrathin layers and multilayers having complicated magnetic structures. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle DAFNE-Light DXR1 Soft X-Ray Synchrotron Radiation Beamline: Characteristics and XAFS Applications
Condens. Matter 2019, 4(1), 7; https://doi.org/10.3390/condmat4010007
Received: 21 November 2018 / Revised: 19 December 2018 / Accepted: 3 January 2019 / Published: 8 January 2019
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Abstract
X-ray Absorption Fine Structure Spectroscopy (XAFS) is a powerful technique to investigate the local atomic geometry and the chemical state of atoms in different types of materials, especially if lacking a long-range order, such as nanomaterials, liquids, amorphous and highly disordered systems, and [...] Read more.
X-ray Absorption Fine Structure Spectroscopy (XAFS) is a powerful technique to investigate the local atomic geometry and the chemical state of atoms in different types of materials, especially if lacking a long-range order, such as nanomaterials, liquids, amorphous and highly disordered systems, and polymers containing metallic atoms. The INFN-LNF DAΦNE-Light DXR1 beam line is mainly dedicated to soft X-ray absorption spectroscopy; it collects the radiation of a wiggler insertion device and covers the energy range from 0.9 to 3.0 keV or the range going from the K-edge of Na through to the K-edge of Cl. The characteristics of the beamline are reported here together with the XAFS spectra of reference compounds, in order to show some of the information achievable with this X-ray spectroscopy. Additionally, some examples of XAFS spectroscopy applications are also reported. Full article
(This article belongs to the Special Issue High Precision X-Ray Measurements)
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Open AccessArticle Improved Single-Crystal Growth of Sr2RuO4
Condens. Matter 2019, 4(1), 6; https://doi.org/10.3390/condmat4010006
Received: 26 November 2018 / Revised: 24 December 2018 / Accepted: 2 January 2019 / Published: 7 January 2019
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Abstract
High-quality single crystals are essentially needed for the investigation of the novel bulk properties of unconventional superconductors. The availability of such crystals grown by the floating-zone method has helped to unveil the unconventional superconductivity of the layered perovskite Sr2RuO4, [...] Read more.
High-quality single crystals are essentially needed for the investigation of the novel bulk properties of unconventional superconductors. The availability of such crystals grown by the floating-zone method has helped to unveil the unconventional superconductivity of the layered perovskite Sr2RuO4, which is considered as a strong candidate of a topological spin-triplet superconductor. Yet, recent progress of investigations urges further efforts to obtain ultimately high-quality crystalline samples. In this paper, we focus on the method of preparation of feed rods for the floating-zone melting and report on the improvements of the crystal growth. We present details of the improved methods used to obtain crystals with superconducting transition temperatures Tc that are consistently as high as 1.4 K, as well as the properties of these crystals. Full article
(This article belongs to the Special Issue Majorana Fermions and Topological Materials Science)
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Open AccessArticle Fingerprint Oxygen Redox Reactions in Batteries through High-Efficiency Mapping of Resonant Inelastic X-ray Scattering
Condens. Matter 2019, 4(1), 5; https://doi.org/10.3390/condmat4010005
Received: 15 December 2018 / Revised: 28 December 2018 / Accepted: 29 December 2018 / Published: 5 January 2019
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Abstract
Realizing reversible reduction-oxidation (redox) reactions of lattice oxygen in batteries is a promising way to improve the energy and power density. However, conventional oxygen absorption spectroscopy fails to distinguish the critical oxygen chemistry in oxide-based battery electrodes. Therefore, high-efficiency full-range mapping of resonant [...] Read more.
Realizing reversible reduction-oxidation (redox) reactions of lattice oxygen in batteries is a promising way to improve the energy and power density. However, conventional oxygen absorption spectroscopy fails to distinguish the critical oxygen chemistry in oxide-based battery electrodes. Therefore, high-efficiency full-range mapping of resonant inelastic X-ray scattering (mRIXS) has been developed as a reliable probe of oxygen redox reactions. Here, based on mRIXS results collected from a series of Li1.17Ni0.21Co0.08Mn0.54O2 electrodes at different electrochemical states and its comparison with peroxides, we provide a comprehensive analysis of five components observed in the mRIXS results. While all the five components evolve upon electrochemical cycling, only two of them correspond to the critical states associated with oxygen redox reactions. One is a specific feature at 531.0 eV excitation and 523.7 eV emission energy, the other is a low-energy loss feature. We show that both features evolve with electrochemical cycling of Li1.17Ni0.21Co0.08Mn0.54O2 electrodes, and could be used for characterizing oxidized oxygen states in the lattice of battery electrodes. This work provides an important benchmark for a complete assignment of all mRIXS features collected from battery materials, which sets a general foundation for future studies in characterization, analysis, and theoretical calculation for probing and understanding oxygen redox reactions. Full article
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Open AccessArticle Substrate-Induced Proximity Effect in Superconducting Niobium Nanofilms
Condens. Matter 2019, 4(1), 4; https://doi.org/10.3390/condmat4010004
Received: 18 November 2018 / Revised: 21 December 2018 / Accepted: 26 December 2018 / Published: 30 December 2018
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Abstract
Structural and superconducting properties of high-quality niobium nanofilms with different thicknesses are investigated on silicon oxide (SiO2) and sapphire substrates. The role played by the different substrates and the superconducting properties of the Nb films are discussed based on the defectivity [...] Read more.
Structural and superconducting properties of high-quality niobium nanofilms with different thicknesses are investigated on silicon oxide (SiO2) and sapphire substrates. The role played by the different substrates and the superconducting properties of the Nb films are discussed based on the defectivity of the films and on the presence of an interfacial oxide layer between the Nb film and the substrate. The X-ray absorption spectroscopy is employed to uncover the structure of the interfacial layer. We show that this interfacial layer leads to a strong proximity effect, especially in films deposited on a SiO2 substrate, altering the superconducting properties of the Nb films. Our results establish that the critical temperature is determined by an interplay between quantum-size effects, due to the reduction of the Nb film thicknesses, and proximity effects. The detailed investigation here provides reference characterizations and has direct and important implications for the fabrication of superconducting devices based on Nb nanofilms. Full article
(This article belongs to the Special Issue Selected Papers from Quantum Complex Matter 2018)
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Open AccessArticle Geometric Effects of a Quarter of Corrugated Torus
Condens. Matter 2019, 4(1), 3; https://doi.org/10.3390/condmat4010003
Received: 1 December 2018 / Revised: 24 December 2018 / Accepted: 24 December 2018 / Published: 28 December 2018
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Abstract
In the spirit of the thin-layer quantization scheme, we give the effective Shrödinger equation for a particle confined to a corrugated torus, in which the geometric potential is substantially changed by corrugation. We find the attractive wells reconstructed by the corrugation not being [...] Read more.
In the spirit of the thin-layer quantization scheme, we give the effective Shrödinger equation for a particle confined to a corrugated torus, in which the geometric potential is substantially changed by corrugation. We find the attractive wells reconstructed by the corrugation not being at identical depths, which is strikingly different from that of a corrugated nanotube, especially in the inner side of the torus. By numerically calculating the transmission probability, we find that the resonant tunneling peaks and the transmission gaps are merged and broadened by the corrugation of the inner side of torus. These results show that the quarter corrugated torus can be used not only to connect two tubes with different radiuses in different directions, but also to filter the particles with particular incident energies. Full article
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