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Condens. Matter, Volume 3, Issue 4 (December 2018)

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Open AccessArticle Effect and Characterization of Stone–Wales Defects on Graphene Quantum Dot: A First-Principles Study
Condens. Matter 2018, 3(4), 50; https://doi.org/10.3390/condmat3040050
Received: 14 November 2018 / Revised: 7 December 2018 / Accepted: 12 December 2018 / Published: 17 December 2018
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Abstract
A first principles based density functional theory (DFT) has been employed to identify the signature of Stone–Wales (SW) defects in semiconducting graphene quantum dot (GQD). Results show that the G mode in the Raman spectra of GQD has been red shifted to 1544.21
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A first principles based density functional theory (DFT) has been employed to identify the signature of Stone–Wales (SW) defects in semiconducting graphene quantum dot (GQD). Results show that the G mode in the Raman spectra of GQD has been red shifted to 1544.21 cm 1 in the presence of 2.08% SW defect concentration. In addition, the intensity ratio between a robust low intense contraction–elongation mode and G mode is found to be reduced for the defected structure. We have also observed a Raman mode at 1674.04 cm 1 due to the solo contribution of the defected bond. The increase in defect concentration, however, reduces the stability of the structures. As a consequence, the systems undergo structural buckling due to the presence of SW defect generated additional stresses. We have further explored that the 1615.45 cm 1 Raman mode and 1619.29 cm 1 infra-red mode are due to the collective stretching of two distinct SW defects separated at a distance 7.98 Å. Therefore, this is the smallest separation between the SW defects for their distinct existence. The pristine structure possesses maximum electrical conductivity and the same reduces to 0.37 times for 2.08% SW defect. On the other hand, the work function is reduced in the presence of defects except for the structure with SW defects separated at 7.98 Å. All these results will serve as an important reference to facilitate the potential applications of GQD based nano-devices with inherent topological SW defects. Full article
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Open AccessArticle Fluctuation Theory in Chemical Kinetics
Condens. Matter 2018, 3(4), 49; https://doi.org/10.3390/condmat3040049
Received: 12 November 2018 / Revised: 11 December 2018 / Accepted: 12 December 2018 / Published: 17 December 2018
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Abstract
In this research, we study the stability properties of chemical reactions of arbitrary orders. In a given chemical experiment, we focus on the formation of a chemical equilibrium by optimizing the reaction rate. Under infinitesimal simultaneous variations of the concentrations of reacting species,
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In this research, we study the stability properties of chemical reactions of arbitrary orders. In a given chemical experiment, we focus on the formation of a chemical equilibrium by optimizing the reaction rate. Under infinitesimal simultaneous variations of the concentrations of reacting species, the binary component equilibrium is achieved when either one of the orders or concentrations of reactants vanishes. The chemical concentration capacities of the components are calculated to describe the local stability of the equilibrium. The correlation between the components is obtained as the mixed second-order derivative of the rate with respect to concentrations. The global stability analysis is performed by introducing a symmetric matrix with its diagonal components as the chemical capacities and off-diagonal components as the local correlation. We find that the local chemical stability requires the orders of the reactants to be either negative or larger than unity. The corresponding global stability requires the positivity of a cubic factor over the orders of the reactants. In short, our consideration illustrates how a chemical reaction takes place by attaining its activation state and asymptotically approaches the equilibrium when two components are mixed with arbitrary orders. Qualitative discussions are provided to support our analysis towards the formation of an optimized equilibrium. Finally, along with future directions, we discuss verification of our model towards the formation of carbon-based reactions, formation of organic/inorganic chemical equilibria and catalytic oxidation of C O H 2 mixtures in presence of Pt. Full article
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Open AccessArticle Fractal Dimension Analysis of High-Resolution X-Ray Phase Contrast Micro-Tomography Images at Different Threshold Levels in a Mouse Spinal Cord
Condens. Matter 2018, 3(4), 48; https://doi.org/10.3390/condmat3040048
Received: 13 July 2018 / Revised: 3 December 2018 / Accepted: 7 December 2018 / Published: 11 December 2018
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Abstract
Fractal analysis is a powerful method for the morphological study of complex systems that is increasingly applied to biomedical images. Spatial resolution and image segmentation are crucial for the discrimination of tissue structures at the multiscale level. In this work, we have applied
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Fractal analysis is a powerful method for the morphological study of complex systems that is increasingly applied to biomedical images. Spatial resolution and image segmentation are crucial for the discrimination of tissue structures at the multiscale level. In this work, we have applied fractal analysis to high-resolution X-ray phase contrast micro-tomography (XrPCμT) images in both uninjured and injured tissue of a mouse spinal cord. We estimated the fractal dimension (FD) using the box-counting method on tomographic slices segmented at different threshold levels. We observed an increased FD in the ipsilateral injured hemicord compared with the contralateral uninjured tissue, which was almost independent of the chosen threshold. Moreover, we found that images exhibited the highest fractality close to the global histogram threshold level. Finally, we showed that the FD estimate largely depends on the image histogram regardless of tissue appearance. Our results demonstrate that the pre-processing of XrPCμT images is critical to fractal analysis and the estimation of FD. Full article
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Open AccessArticle Iron Speciation in Insoluble Dust from High-Latitude Snow: An X-ray Absorption Spectroscopy Study
Condens. Matter 2018, 3(4), 47; https://doi.org/10.3390/condmat3040047
Received: 1 October 2018 / Revised: 29 November 2018 / Accepted: 3 December 2018 / Published: 10 December 2018
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Abstract
Iron is thought to limit the biomass of phytoplankton populations in extensive regions of the ocean, which are referred to as high-nutrient low-chlorophyll (HNLC) regions. Iron speciation in soils is still poorly understood. We have investigated inorganic and organic standard substances, diluted mixtures
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Iron is thought to limit the biomass of phytoplankton populations in extensive regions of the ocean, which are referred to as high-nutrient low-chlorophyll (HNLC) regions. Iron speciation in soils is still poorly understood. We have investigated inorganic and organic standard substances, diluted mixtures of common Fe minerals in insoluble dust in snow from the Laohugou No.12 glacier, and sand (including soil and moraine) samples that were collected from western China. The speciation of iron (Fe) in insoluble dust and sand was determined by X-ray absorption near-edge structure (XANES) spectroscopy. A linear fit combination (LCF) analysis of the experimental spectra compared to a large set of reference compounds showed that all spectra can be fitted by only four species: Fe2O3, Fe3O4, biotite, and ferrous oxalate dihydrate (FOD). A significant altitude effect was detected for snow. The proportion of Fe2O3 in snow decreases gradually, and vice versa for FOD. As for Fe3O4 and biotite, the altitude effect was also detected, but separate regions should be considered to be deduced by topography. The Fe species in moraines and soils were also analyzed to identify the source of moraines and the heterogeneity of soils, and were compared with snow. Full article
(This article belongs to the Special Issue Condensed Matter Researches in Cryospheric Science)
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Open AccessArticle A Computational Study on the Variation of Bandgap Due to Native Defects in Non-Stoichiometric NiO and Pd, Pt Doping in Stoichiometric NiO
Condens. Matter 2018, 3(4), 46; https://doi.org/10.3390/condmat3040046
Received: 21 October 2018 / Revised: 1 December 2018 / Accepted: 6 December 2018 / Published: 7 December 2018
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Abstract
This paper presents a computational study of non-stoichiometric nickel oxide in a 64-cell NiO system to model and validate localized heating effects due to nanosecond laser irradiation. Variation in the Bandgap of NiO is studied as a function of varying concentrations of native
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This paper presents a computational study of non-stoichiometric nickel oxide in a 64-cell NiO system to model and validate localized heating effects due to nanosecond laser irradiation. Variation in the Bandgap of NiO is studied as a function of varying concentrations of native defects, ranging from 0 to 25%. It is observed that there is a slight increase in the bandgap from 3.80 eV for stoichiometric NiO to 3.86 eV for Ni-rich NiO and to 3.95 eV for O-rich NiO. It is hence deduced that the experimental laser irradiation leads to simultaneous reduction of Ni2+ ions and the oxidation of NiO as the number of laser pulses increase. As well, a detailed study on the effects of doping nickel family elements, i.e., palladium (Pd) and platinum (Pt), in stoichiometric NiO is presented. A bandgap decrease from 3.8 eV for pure NiO to 2.5 eV for Pd-doping and 2.0 eV for Pt-doping for varying doping concentrations ranging from 0–25% Pd, Pt, respectively, is observed. Full article
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Open AccessArticle XANES Iron Geochemistry in the Mineral Dust of the Talos Dome Ice Core (Antarctica) and the Southern Hemisphere Potential Source Areas
Condens. Matter 2018, 3(4), 45; https://doi.org/10.3390/condmat3040045
Received: 27 June 2018 / Revised: 2 November 2018 / Accepted: 22 November 2018 / Published: 6 December 2018
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Abstract
X-ray absorption near edge structure (XANES) measurements at the Fe K-edge were performed on aeolian dust in the TALos Dome Ice CorE drilling project (TALDICE) ice core drilled in the peripheral East Antarctic plateau, as well as on Southern Hemisphere potential source area
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X-ray absorption near edge structure (XANES) measurements at the Fe K-edge were performed on aeolian dust in the TALos Dome Ice CorE drilling project (TALDICE) ice core drilled in the peripheral East Antarctic plateau, as well as on Southern Hemisphere potential source area samples. While South American sources show, as expected, a progressive increase in Fe oxidation with decreasing latitude, Antarctic sources show Fe oxidation levels higher than expected in such a cold polar environment, probably because of their very high exposure ages. Results from the TALDICE dust samples are compatible with a South American influence at the site during MIS2 (marine isotopic stage 2, the last and coldest phase of the last glacial period), in particular from Patagonia and Tierra del Fuego. However, a contribution from Australia and/or local Antarctic sources cannot be ruled out. Finally, important changes also occurred during the deglaciation and in the Holocene, when the influence of Antarctic local sources seems to have become progressively more important in recent times. This research is the first successful attempt to extract temporal climatic information from X-ray absorption spectroscopic data of the insoluble mineral dust particles contained in an ice core and shows the high potential of this technique. Full article
(This article belongs to the Special Issue Condensed Matter Researches in Cryospheric Science)
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Open AccessArticle Complex Dielectric and Impedance Spectroscopic Studies in a Multiferroic Composite of Bi2Fe4O9-BiFeO3
Condens. Matter 2018, 3(4), 44; https://doi.org/10.3390/condmat3040044
Received: 4 November 2018 / Revised: 24 November 2018 / Accepted: 28 November 2018 / Published: 2 December 2018
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Abstract
Complex dielectric and impedance spectroscopic studies have been carried out in a detailed manner on the system comprising of Bi2Fe4O9-BiFeO3 composite particles dispersed in a α-Fe2O3 matrix as prepared using ball milling and
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Complex dielectric and impedance spectroscopic studies have been carried out in a detailed manner on the system comprising of Bi2Fe4O9-BiFeO3 composite particles dispersed in a α-Fe2O3 matrix as prepared using ball milling and controlled annealing treatments. This multiferroic composite is observed to exhibit a giant dielectric constant associated with a low tangent loss. A non-Debye type of relaxation has been deduced based on complex modulus analysis. Based on these studies, the important role played by bismuth ferrite nanoshell in the core-shell composite of Bi2Fe4O9-BiFeO3 is elucidated for the observed complex impedance spectroscopic properties of the system. Electron hopping across Fe2+/Fe3+ and oxygen vacancies are deduced to be playing an important role in conduction mechanisms based on activation energy analysis of the complex impedance spectroscopy results. Full article
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Open AccessArticle Electric Polarization in Magnetic Topological Nodal Semimetal Thin Films
Condens. Matter 2018, 3(4), 43; https://doi.org/10.3390/condmat3040043
Received: 1 November 2018 / Revised: 23 November 2018 / Accepted: 28 November 2018 / Published: 30 November 2018
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Abstract
We theoretically study the electric polarization in magnetic topological nodal semimetal thin films. In magnetically doped topological insulators, topological nodal semimetal phases emerge once the exchange coupling overcomes the band gap. Changing the magnetization direction, nodal structure is modulated and the system becomes
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We theoretically study the electric polarization in magnetic topological nodal semimetal thin films. In magnetically doped topological insulators, topological nodal semimetal phases emerge once the exchange coupling overcomes the band gap. Changing the magnetization direction, nodal structure is modulated and the system becomes topological nodal point or line semimetals. We find that nodal line semimetals are characterized by non-linear electric polarization, which is not observed in nodal point semimetals. The non-linear response originates from the existence of the surface states. Screening effect is self consistently included within a mean field approximation and the non-linear electric polarization is observed even in the presence of screening effect. Full article
(This article belongs to the Special Issue Majorana Fermions and Topological Materials Science)
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Open AccessArticle The Magnetic Properties of 1111-type Diluted Magnetic Semiconductor (La1−xBax)(Zn1−xMnx)AsO in the Low Doping Regime
Condens. Matter 2018, 3(4), 42; https://doi.org/10.3390/condmat3040042
Received: 14 September 2018 / Revised: 15 November 2018 / Accepted: 26 November 2018 / Published: 29 November 2018
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Abstract
We investigated the magnetic properties of (La1xBax)(Zn1xMnx)AsO with x varying from 0.005 to 0.05 at an external magnetic field of 1000 Oe. For doping levels of x ≤ 0.01, the system
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We investigated the magnetic properties of (La 1 x Ba x )(Zn 1 x Mn x )AsO with x varying from 0.005 to 0.05 at an external magnetic field of 1000 Oe. For doping levels of x ≤ 0.01, the system remains paramagnetic down to the lowest measurable temperature of 2 K. Only when the doping level increases to x = 0.02 does the ferromagnetic ordering appear. Our analysis indicates that antiferromagnetic exchange interactions dominate for x ≤ 0.01, as shown by the negative Weiss temperature fitted from the magnetization data. The Weiss temperature becomes positive, i.e., ferromagnetic coupling starts to dominate, for x ≥ 0.02. The Mn-Mn spin interaction parameter 2 J / k B is estimated to be in the order of 10 K for both x ≤ 0.01 (antiferromagnetic ordered state) and x ≥ 0.02 (ferromagnetic ordered state). Our results unequivocally demonstrate the competition between ferromagnetic and antiferromagnetic exchange interactions in carrier-mediated ferromagnetic systems. Full article
(This article belongs to the Special Issue Selected Papers from Quantum Complex Matter 2018)
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Open AccessArticle Surface Excitations, Shape Deformation, and the Long-Time Behavior in a Stirred Bose–Einstein Condensate
Condens. Matter 2018, 3(4), 41; https://doi.org/10.3390/condmat3040041
Received: 10 September 2018 / Revised: 21 November 2018 / Accepted: 23 November 2018 / Published: 25 November 2018
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Abstract
The surface excitations, shape deformation, and the formation of persistent current for a Gaussian obstacle potential rotating in a highly oblate Bose–Einstein condensate (BEC) are investigated. A vortex dipole can be produced and trapped in the center of the stirrer even for the
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The surface excitations, shape deformation, and the formation of persistent current for a Gaussian obstacle potential rotating in a highly oblate Bose–Einstein condensate (BEC) are investigated. A vortex dipole can be produced and trapped in the center of the stirrer even for the slow motion of the stirring beam. When the angular velocity of the obstacle is above some critical value, the condensate shape can be deformed remarkably at the corresponding rotation frequency followed by surface wave excitations. After a long enough time, a small number of vortices are found to be either trapped in the condensate or pinned by the obstacle, and a vortex dipole or several vortices can be trapped at the beam center, which provides another way to manipulate the vortex. Full article
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Open AccessArticle Seeking to Develop Global SYK-Ness
Condens. Matter 2018, 3(4), 40; https://doi.org/10.3390/condmat3040040
Received: 4 October 2018 / Revised: 11 November 2018 / Accepted: 13 November 2018 / Published: 15 November 2018
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Abstract
Inspired by the recent interest in the Sachdev–Ye–Kitaev (SYK) model, we study a class of multi-flavored one- and two-band fermion systems with no bare dispersion. In contrast to the previous work on the SYK model that would routinely assume spatial locality, thus unequivocally
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Inspired by the recent interest in the Sachdev–Ye–Kitaev (SYK) model, we study a class of multi-flavored one- and two-band fermion systems with no bare dispersion. In contrast to the previous work on the SYK model that would routinely assume spatial locality, thus unequivocally arriving at the so-called ‘locally-critical’ scenario, we seek to attain a spatially-dispersing ‘globally-SYK’ behavior. To that end, a variety of the Lorentz-(non)invariant space-and/or-time dependent algebraically decaying interaction functions is considered and some of the thermodynamic and transport properties of such systems are discussed. Full article
Open AccessArticle Negative Energy Antiferromagnetic Instantons Forming Cooper-Pairing ‘Glue’ and ‘Hidden Order’ in High-Tc Cuprates
Condens. Matter 2018, 3(4), 39; https://doi.org/10.3390/condmat3040039
Received: 29 September 2018 / Revised: 29 October 2018 / Accepted: 3 November 2018 / Published: 7 November 2018
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Abstract
An emergence of magnetic boson of instantonic nature, that provides a Cooper-‘pairing glue’, is considered in the repulsive ‘nested’ Hubbard model of superconducting cuprates. It is demonstrated that antiferromagnetic instantons of a spin density wave type may have negative energy due to coupling
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An emergence of magnetic boson of instantonic nature, that provides a Cooper-‘pairing glue’, is considered in the repulsive ‘nested’ Hubbard model of superconducting cuprates. It is demonstrated that antiferromagnetic instantons of a spin density wave type may have negative energy due to coupling with Cooper pair condensate. A set of Eliashberg like equations is derived and solved self-consistently, proving the above suggestion. An instantonic propagator plays the role of the Green function of the pairing ‘glue’ boson. Simultaneously, the instantons defy condensation of the mean-field spin-density wave (SDW) order. We had previously demonstrated in analytical form that periodic chain of instanton-anti-instanton pairs along the axis of Matsubara time has zero scattering cross section for weakly perturbing external probes, like neutrons, etc., thus representing a ‘hidden order’. Hence, the two competing orders, superconducting and antiferromagnetic, may coexist (below some T c ) in the form of the superconducting order coupled to ‘hidden’ instantonic one. This new picture is discussed in relation with the mechanism of high temperature superconductivity. Full article
(This article belongs to the Special Issue Selected Papers from Quantum Complex Matter 2018)
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Open AccessArticle Localization Parameters for Two Interacting Particles in Disordered Two-Dimensional Finite Lattices
Condens. Matter 2018, 3(4), 38; https://doi.org/10.3390/condmat3040038
Received: 15 September 2018 / Revised: 26 October 2018 / Accepted: 28 October 2018 / Published: 30 October 2018
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Abstract
I study spreading of two interacting hardcore bosons in disordered two-dimensional finite lattices from an initial occupation of two adjacent sites. The parameters related to the spreading of the particles provide an insight on the effect of interaction. I find that the presence
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I study spreading of two interacting hardcore bosons in disordered two-dimensional finite lattices from an initial occupation of two adjacent sites. The parameters related to the spreading of the particles provide an insight on the effect of interaction. I find that the presence of interaction makes the particles less localized than the non-interacting ones within the range of disorder strength W 4 and interaction strength V 4 . If the interaction strength is higher, then particles localize more. A transition with changes in the character of dominant correlations is found at critical disorder strengths for each chosen strength of interaction. The nature of correlations between the particles as nearest neighbours becomes dominant beyond these disorder strengths. Full article
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Open AccessArticle Majorana Fermions in One-Dimensional Structures at LaAlO3/SrTiO3 Oxide Interfaces
Condens. Matter 2018, 3(4), 37; https://doi.org/10.3390/condmat3040037
Received: 1 October 2018 / Revised: 19 October 2018 / Accepted: 26 October 2018 / Published: 29 October 2018
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Abstract
We study one-dimensional structures that may be formed at the LaAlO3/SrTiO3 oxide interface by suitable top gating. These structures are modeled via a single-band model with Rashba spin-orbit coupling, superconductivity and a magnetic field along the one-dimensional chain. We first
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We study one-dimensional structures that may be formed at the LaAlO 3 /SrTiO 3 oxide interface by suitable top gating. These structures are modeled via a single-band model with Rashba spin-orbit coupling, superconductivity and a magnetic field along the one-dimensional chain. We first discuss the conditions for the occurrence of a topological superconducting phase and the related formation of Majorana fermions at the chain endpoints, highlighting a close similarity between this model and the Kitaev model, which also reflects in a similar condition the formation of a topological phase. Solving the model in real space, we also study the spatial extension of the wave function of the Majorana fermions and how this increases with approaching the limit condition for the topological state. Using a scattering matrix formalism, we investigate the stability of the Majorana fermions in the presence of disorder and discuss the evolution of the topological phase with increasing disorder. Full article
(This article belongs to the Special Issue Selected Papers from Quantum Complex Matter 2018)
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Open AccessArticle Operando XAFS and XRD Study of a Prussian Blue Analogue Cathode Material: Iron Hexacyanocobaltate
Condens. Matter 2018, 3(4), 36; https://doi.org/10.3390/condmat3040036
Received: 9 October 2018 / Revised: 18 October 2018 / Accepted: 23 October 2018 / Published: 25 October 2018
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Abstract
The reversible electrochemical lithiation of potassium iron hexacyanocobaltate (FeCo) was studied by operando X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) assisted by chemometric techniques. In this way, it was possible to follow the system dynamics and retrieve structural and electronic transformations
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The reversible electrochemical lithiation of potassium iron hexacyanocobaltate (FeCo) was studied by operando X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) assisted by chemometric techniques. In this way, it was possible to follow the system dynamics and retrieve structural and electronic transformations along cycling at both Fe and Co sites. These analyses confirmed that FeCo features iron as the main electroactive site. Even though the release of potassium ions causes a local disorder around the iron site, the material exhibits an excellent structural stability during the alkali ion deinsertion/insertion processes. An independent but interrelated analysis approach offers a good strategy for data treatment and provides a time-resolved picture of the studied system. Full article
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Open AccessArticle Exponents of Spectral Functions in the One-Dimensional Bose Gas
Condens. Matter 2018, 3(4), 35; https://doi.org/10.3390/condmat3040035
Received: 20 September 2018 / Revised: 13 October 2018 / Accepted: 16 October 2018 / Published: 23 October 2018
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Abstract
The one-dimensional gas of bosons interacting via a repulsive contact potential was solved long ago via Bethe’s ansatz by Lieb and Liniger (Exact Analysis of an Interacting Bose Gas. I. The General Solution and the Ground State). The low energy excitation spectrum is
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The one-dimensional gas of bosons interacting via a repulsive contact potential was solved long ago via Bethe’s ansatz by Lieb and Liniger (Exact Analysis of an Interacting Bose Gas. I. The General Solution and the Ground State). The low energy excitation spectrum is a Luttinger liquid parametrized by a conformal field theory with conformal charge c = 1 . For higher energy excitations the spectral function displays deviations from the Luttinger behavior arising from the curvature terms in the dispersion. Adding a corrective term of the form of a mobile impurity coupled to the Luttinger liquid modes corrects this problem. The “impurity” term is an irrelevant operator, which if treated non-perturbatively, yields the threshold singularities in the one-particle and one-hole Green’s function correctly. We show that the exponents obtained via the finite size corrections to the ground state energy are identical to those obtained through the shift function. Full article
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Open AccessArticle Bandgap Tunability in a One-Dimensional System
Condens. Matter 2018, 3(4), 34; https://doi.org/10.3390/condmat3040034
Received: 20 September 2018 / Revised: 18 October 2018 / Accepted: 20 October 2018 / Published: 22 October 2018
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Abstract
The ability to tune the gaps of direct bandgap materials has tremendous potential for applications in the fields of LEDs and solar cells. However, lack of reproducibility of bandgaps due to quantum confinement observed in experiments on reduced dimensional materials, severely affects tunability
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The ability to tune the gaps of direct bandgap materials has tremendous potential for applications in the fields of LEDs and solar cells. However, lack of reproducibility of bandgaps due to quantum confinement observed in experiments on reduced dimensional materials, severely affects tunability of their bandgaps. In this article, we report broad theoretical investigations of direct bandgap one-dimensional functionalized isomeric system using their periodic potential profile, where bandgap tunability is demonstrated simply by modifying the potential profile by changing the position of the functional group in a periodic supercell. We found that bandgap in one-dimensional isomeric systems having the same functional group depends upon the width and depth of the deepest potential well at global minimum and derived correlations are verified for known synthetic as well as natural polymers (biological and organic), and also for other one-dimensional direct bandgap systems. This insight would greatly help experimentalists in designing new isomeric systems with different bandgap values for polymers and one-dimensional inorganic systems for possible applications in LEDs and solar cells. Full article
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Open AccessArticle Challenging X-ray Fluorescence Applications for Environmental Studies at XLab Frascati
Condens. Matter 2018, 3(4), 33; https://doi.org/10.3390/condmat3040033
Received: 31 July 2018 / Revised: 8 October 2018 / Accepted: 12 October 2018 / Published: 18 October 2018
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Abstract
In this work, we will report applications of the total external X-ray fluorescence (TXRF) station, a prototype assembled at the XLab Frascati laboratory (XlabF) at the INFN National Laboratories of Frascati (INFN LNF). XlabF has been established as a facility to study, design
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In this work, we will report applications of the total external X-ray fluorescence (TXRF) station, a prototype assembled at the XLab Frascati laboratory (XlabF) at the INFN National Laboratories of Frascati (INFN LNF). XlabF has been established as a facility to study, design and develop X-ray optics, in particular, polycapillary lenses, as well as to perform X-ray experiments for both elemental analysis and tomography. The combination of low-power conventional sources and policapillary optics allows assembling a prototype that can provide a quasi-parallel intense beam for detailed X-ray spectroscopic analysis of extremely low concentrated samples, down to ng/g. We present elemental analysis results of elements contained in tree rings and of dust stored in deep ice cores. In addition to performing challenging environmental research studies, other experiments aim to characterize novel optics and to evaluate original experimental schemes for X-ray diffraction (XRD), X-ray fluorescence (XRF and TXRF) and X-ray imaging. Full article
(This article belongs to the Special Issue Condensed Matter Researches in Cryospheric Science)
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Open AccessBrief Report Exact Solutions and Degenerate Properties of Spin Chains with Reducible Hamiltonians
Condens. Matter 2018, 3(4), 32; https://doi.org/10.3390/condmat3040032
Received: 15 September 2018 / Revised: 7 October 2018 / Accepted: 13 October 2018 / Published: 15 October 2018
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Abstract
The Jordan–Wigner transformation plays an important role in spin models. However, the non-locality of the transformation implies that a periodic chain of N spins is not mapped to a periodic or an anti-periodic chain of lattice fermions. Since only the N1
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The Jordan–Wigner transformation plays an important role in spin models. However, the non-locality of the transformation implies that a periodic chain of N spins is not mapped to a periodic or an anti-periodic chain of lattice fermions. Since only the N 1 bond is different, the effect is negligible for large systems, while it is significant for small systems. In this paper, it is interesting to find that a class of periodic spin chains can be exactly mapped to a periodic chain and an anti-periodic chain of lattice fermions without redundancy when the Jordan–Wigner transformation is implemented. For these systems, possible high degeneracy is found to appear in not only the ground state, but also the excitation states. Further, we take the one-dimensional compass model and a new XY-XY model ( σ x σ y σ x σ y ) as examples to demonstrate our proposition. Except for the well-known one-dimensional compass model, we will see that in the XY-XY model, the degeneracy also grows exponentially with the number of sites. Full article
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Open AccessArticle Effect of the Strength of Attraction Between Nanoparticles on Wormlike Micelle- Nanoparticle System
Condens. Matter 2018, 3(4), 31; https://doi.org/10.3390/condmat3040031
Received: 31 August 2018 / Revised: 7 October 2018 / Accepted: 10 October 2018 / Published: 13 October 2018
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Abstract
The nanoparticle-Equilibrium polymer (or Wormlike micellar) system shows morphological changes from percolating network-like structures to non-percolating clusters with a change in the minimum approaching distance (EVP-excluded volume parameter) between nanoparticles and the matrix of equilibrium polymers. The shape anisotropy of nanoparticle clusters can
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The nanoparticle-Equilibrium polymer (or Wormlike micellar) system shows morphological changes from percolating network-like structures to non-percolating clusters with a change in the minimum approaching distance (EVP-excluded volume parameter) between nanoparticles and the matrix of equilibrium polymers. The shape anisotropy of nanoparticle clusters can be controlled by changing the polymer density. In this paper, the synergistic self-assembly of nanoparticles inside equilibrium polymeric matrix (or Wormlike micellar matrix) is investigated with respect to the change in the strength of attractive interaction between nanoparticles. A shift in the point of morphological transformation of the system to lower values of EVP as a result of a decrease in the strength of the attractive nanoparticle interaction is reported. We show that the absence of the attractive interaction between nanoparticles leads to the low packing of nanoparticle structures, but does not change the morphological behavior of the system. We also report the formation of the system spanning sheet-like arrangement of nanoparticles which are arranged in alternate layers of matrix polymers and nanoparticles. Full article
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Open AccessReview Anomalous Transport Behavior in Quantum Magnets
Condens. Matter 2018, 3(4), 30; https://doi.org/10.3390/condmat3040030
Received: 25 September 2018 / Revised: 2 October 2018 / Accepted: 6 October 2018 / Published: 10 October 2018
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Abstract
Transport behavior that is characterized by a low-temperature electrical resistivity that displays a power law behavior (ρ(T0)Ts) with an exponent of s<2 is commonly observed in magnetic materials in both the
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Transport behavior that is characterized by a low-temperature electrical resistivity that displays a power law behavior ( ρ ( T 0 ) T s ) with an exponent of s < 2 is commonly observed in magnetic materials in both the magnetic and non-magnetic phases. We give a pedagogical overview of this phenomenon that summarizes both the experimental situation and the state of its theoretical understanding. We also put it in context by drawing parallels with unusual power law transport behavior in other systems. Full article
(This article belongs to the Special Issue Selected Papers from Quantum Complex Matter 2018)
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Open AccessReview Perspectives of XRF and XANES Applications in Cryospheric Sciences Using Chinese SR Facilities
Condens. Matter 2018, 3(4), 29; https://doi.org/10.3390/condmat3040029
Received: 6 September 2018 / Revised: 29 September 2018 / Accepted: 29 September 2018 / Published: 8 October 2018
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Abstract
As an important part of the climate system, the cryosphere, can be studied with a variety of techniques based on laboratory-based or field-portable equipment in order to accumulate data for a better understanding of this portion of the Earth’s surface. The advent of
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As an important part of the climate system, the cryosphere, can be studied with a variety of techniques based on laboratory-based or field-portable equipment in order to accumulate data for a better understanding of this portion of the Earth’s surface. The advent of synchrotron radiation (SR) facilities as large scientific interdisciplinary infrastructures has reshaped the scenario of these investigations and, in particular, of condensed matters researches. Many spectroscopic methods allow for characterizing the structure or electronic structure of samples, while the scattering/diffraction methods enable the determination of crystalline structures of either organic or inorganic systems. Moreover, imaging methods offer an unprecedented spatial resolution of samples, revealing their inner structure and morphology. In this contribution, we briefly introduce the SR facilities now available in mainland China, and the perspectives of SR-based methods suitable to investigate ice, snow, aerosols, dust, and other samples of cryospheric origin from deep ice cores, permafrost, filters, etc. The goal is to deepen the understanding in cryospheric sciences through an increased collaboration between the synchrotron radiation community and the scientists working in polar areas or involved in correlated environmental problems. Full article
(This article belongs to the Special Issue Condensed Matter Researches in Cryospheric Science)
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Open AccessArticle A Monte-Carlo Study on the Coupling of Magnetism and Ferroelectricity in the Hexagonal Multiferroic RMnO3
Condens. Matter 2018, 3(4), 28; https://doi.org/10.3390/condmat3040028
Received: 15 August 2018 / Revised: 16 September 2018 / Accepted: 18 September 2018 / Published: 20 September 2018
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Abstract
The ferroelectric phase transition in RMnO3 breaks both Z3 and Z2 symmetries, giving rise to 6 structural domains. Topological protected vortices are formed at the junctions of all 6 domains, and the ferroelectric phase transition is closely related to these
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The ferroelectric phase transition in RMnO3 breaks both Z3 and Z2 symmetries, giving rise to 6 structural domains. Topological protected vortices are formed at the junctions of all 6 domains, and the ferroelectric phase transition is closely related to these Z6 vortices. In this work, Monte-Carlo studies on both the ferroelectric and magnetic transition have been performed on RMnO3 system. The magnetic simulation results on lattices with different structural domain distributions induced by external electric field and simulated quenching show different magnetic transition temperature T s , indicating that the coupling of magnetism and ferroelectricity is through the Z6 structural domain. At extreme case, lattice quenched from above the ferroelectric transition results in high vortex density, which can drive the system into spin glass. Full article
(This article belongs to the Special Issue New Trends in Quantum Complex Matter)
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