Journal Description
Condensed Matter
Condensed Matter
is an international, peer-reviewed, open access journal on the physics of condensed matter published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 21 days after submission; acceptance to publication is undertaken in 4.8 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
1.9 (2023);
5-Year Impact Factor:
1.5 (2023)
Latest Articles
From Phonons to Domain Walls, the Central Peak and “Critical Slowing Down”
Condens. Matter 2024, 9(4), 39; https://doi.org/10.3390/condmat9040039 - 1 Oct 2024
Abstract
We investigate perovskite oxides from different perspectives, namely their pseudo-harmonic dynamical properties, their dynamical properties when strong anharmonicity exists, and the intriguing functionalities arising from domain walls. Taking these viewpoints together yields a rather complex picture of this material class, which has not
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We investigate perovskite oxides from different perspectives, namely their pseudo-harmonic dynamical properties, their dynamical properties when strong anharmonicity exists, and the intriguing functionalities arising from domain walls. Taking these viewpoints together yields a rather complex picture of this material class, which has not been found in previous approaches. It opens pathways to novel applications and reveals the rich ground states beyond the fictitious belief in the ‘simplicity of perovskites and such structures’.
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(This article belongs to the Special Issue Complexity in Quantum Materials: In Honor of Prof. K.A. Muller)
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Undamped Higgs Modes in Strongly Interacting Superconductors
by
José Lorenzana and Götz Seibold
Condens. Matter 2024, 9(4), 38; https://doi.org/10.3390/condmat9040038 - 30 Sep 2024
Abstract
In superconductors, gauge symmetry is spontaneously broken. According to Goldstone’s theorem, this breaking of a continuous symmetry establishes the existence of the Bogoliubov phase mode while the gauge-invariant response also includes the amplitude fluctuations of the order parameter. The
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In superconductors, gauge symmetry is spontaneously broken. According to Goldstone’s theorem, this breaking of a continuous symmetry establishes the existence of the Bogoliubov phase mode while the gauge-invariant response also includes the amplitude fluctuations of the order parameter. The latter, which are also termed ‘Higgs’ modes in analogy with the standard model, appear at the energy of the spectral gap , when the superconducting ground state is evaluated within the weak-coupling BCS theory, and, therefore, are damped. Previously, we have shown that, within the time-dependent Gutzwiller approximation (TDGA), Higgs modes appear inside the gap with a finite binding energy relative to the quasiparticle continuum. Here, we show that the binding energy of the Higgs mode becomes exponentially small in the weak-coupling limit converging to the BCS solution. On the other hand, well-defined undamped amplitude modes exist in strongly coupled superconductors when the interaction energy becomes of the order of the bandwidth.
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(This article belongs to the Special Issue Superstripes Physics, 3rd Edition)
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Angularly Selective Enhanced Vortex Screening in Extremely Layered Superconductors with Tilted Columnar Defects
by
Gonzalo Rumi, Vincent Mosser, Marcin Konczykowski and Yanina Fasano
Condens. Matter 2024, 9(4), 37; https://doi.org/10.3390/condmat9040037 - 27 Sep 2024
Abstract
We report on two mechanisms of angularly selective enhanced screening in the solid vortex phase of extremely layered superconductors with tilted columnar defects (CDs). We study Bi2Sr2CaCu2O8+δ samples with different densities of CD tilted 45°
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We report on two mechanisms of angularly selective enhanced screening in the solid vortex phase of extremely layered superconductors with tilted columnar defects (CDs). We study Bi2Sr2CaCu2O8+δ samples with different densities of CD tilted 45° from the c-axis, and conduct local ac Hall magnetometry measurements, probing the sustainable current of the vortex system. We reveal two types of maxima in sustainable current for particular directions, detected as dips in the magnetic transmittivity of the vortex system. First, for a smaller number of vortices than of defects, an enhancement of screening is detected at an angular location ∼45° for H applied close to the direction of CD. For a larger number of vortices than of CD, decreases towards the -plane direction upon warming. Second, a pair of additional dips in transmittivity are detected at angles closer to, and quite symmetric with, the -plane. These two types of angularly selective enhanced screening reveal the effective pinning by tilted CD even for the composite vortex lattices nucleated in tilted fields in Bi2Sr2CaCu2O8+δ.
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(This article belongs to the Section Superconductivity)
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Collision Dynamics of One-Dimensional Bose–Einstein Condensates
by
Aaron Wirthwein, Stephan Haas and Sheng-wey Chiow
Condens. Matter 2024, 9(4), 36; https://doi.org/10.3390/condmat9040036 - 27 Sep 2024
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We study the collision dynamics of two Bose–Einstein condensates, with their dynamical wave functions modeled by a set of coupled, time-dependent Gross–Pitaevskii equations. In an effective one-dimensional system, we identify regimes characterized by the relationship between inter- and intra-atomic interactions and the initial
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We study the collision dynamics of two Bose–Einstein condensates, with their dynamical wave functions modeled by a set of coupled, time-dependent Gross–Pitaevskii equations. In an effective one-dimensional system, we identify regimes characterized by the relationship between inter- and intra-atomic interactions and the initial configuration of the system, akin to the equilibrium phase diagram of two interacting Bose condensates. We consider a dynamical setup in which two wave packets are initially at rest, with a small separation about the center of an anisotropic harmonic trap. Upon release, we observe a rapid approach to dynamical equilibrium in the limits of very large and very small inter-particle repulsion, characterized by periodic transmission or reflection of the condensates as distinguishable units, whereas the intermediate, critical regime is characterized by extended transient dynamics, density fracturing, and dynamical mixing.
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Towards the Construction of an Analog Solver for the Schrödinger and Ginzburg–Landau Equations Based on a Transmission Line
by
Krzysztof Pomorski, Łukasz Pluszyński and Eryk Hałubek
Condens. Matter 2024, 9(4), 35; https://doi.org/10.3390/condmat9040035 - 26 Sep 2024
Abstract
The model presented by Gabriel Kron in 1945 is an example of an analog computer simulating quantum phenomena on a hardware level. It uses passive RLC elements to construct a hardware solver for the problem of quantum particles confined by rectangular or other
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The model presented by Gabriel Kron in 1945 is an example of an analog computer simulating quantum phenomena on a hardware level. It uses passive RLC elements to construct a hardware solver for the problem of quantum particles confined by rectangular or other classes of potential. The analytical and numerical validation of Kron’s second model is conducted for different shapes of particle-confining potentials in the one-dimensional case using an LTspice simulator. Thus, there remains potential for obtaining solutions in two- and three-dimensional cases. Here, a circuit model representing a linearized Ginzburg–Landau equation is given. Kron’s second model is generalized by the introduction of linear and non-linear resistive elements. This transforms the deformed Schrödinger equation into a linear dissipative Schrödinger equation and its non-linear form. The quantum mechanical roton problem is the main result of this work and is formulated by means of classical physical states naturally present in the LC classical circular electrical transmission line. The experimental verification of Kron’s model is confirmed.
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(This article belongs to the Special Issue Selected Papers from the International Conference on Quantum Materials and Technologies (ICQMT2024))
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Room-Temperature Superconductivity in 1D
by
Carlo A. Trugenberger
Condens. Matter 2024, 9(3), 34; https://doi.org/10.3390/condmat9030034 - 8 Sep 2024
Abstract
We review the theoretical model underpinning the recently reported room-temperature, ambient-pressure superconductivity along line defects on the surface of highly oriented pyrolytic graphite. The main ingredients for this 1D room-temperature superconductivity are pairing by effective strain gauge fields, the formation of an effective
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We review the theoretical model underpinning the recently reported room-temperature, ambient-pressure superconductivity along line defects on the surface of highly oriented pyrolytic graphite. The main ingredients for this 1D room-temperature superconductivity are pairing by effective strain gauge fields, the formation of an effective Josephson junction array in its Bose metal state on the surface and the suppression of phase slips by dimensional embedding in an extremely well-conducting 3D bulk structure.
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(This article belongs to the Special Issue Superstripes Physics, 3rd Edition)
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Remarks on the Quantum Effects of Screw Dislocation Topology and Missing Magnetic Flux
by
Knut Bakke
Condens. Matter 2024, 9(3), 33; https://doi.org/10.3390/condmat9030033 - 8 Aug 2024
Abstract
We revisit the interaction between a point charge and an inhomogeneous magnetic field that yields the magnetic quantum dot system. This magnetic field is defined by filling the whole space, except for a region of radius . Then, we assume that
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We revisit the interaction between a point charge and an inhomogeneous magnetic field that yields the magnetic quantum dot system. This magnetic field is defined by filling the whole space, except for a region of radius . Then, we assume that there is an impenetrable potential wall located at and discuss the quantum effects of screw dislocation topology and the missing magnetic flux. We first show that Landau levels can be achieved even though there is the presence of an impenetrable potential wall. We go further by discussing the confinement of a point charge to a cylindrical wire. In both cases, we show Aharonov–Bohm-type effects for bound states can be obtained from the influence of the screw dislocation topology and the missing magnetic flux. Later, we discuss the influence of the screw dislocation topology and the missing magnetic flux on the magnetization and the persistent currents.
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(This article belongs to the Section Condensed Matter Theory)
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Atomristor Mott Theory of Sn Adatom Adlayer on a Si Surface
by
Luis Craco, Edson F. Chagas, Sabrina S. Carara and Byron Freelon
Condens. Matter 2024, 9(3), 32; https://doi.org/10.3390/condmat9030032 - 2 Aug 2024
Abstract
We use a combination of density functional theory (DFT) and dynamical mean field theory (DMFT) to unveil orbital field-induced electronic structure reconstruction of the atomic Sn layer deposited onto a Si(111) surface (Sn/Si(111)− ), also referred to
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We use a combination of density functional theory (DFT) and dynamical mean field theory (DMFT) to unveil orbital field-induced electronic structure reconstruction of the atomic Sn layer deposited onto a Si(111) surface (Sn/Si(111)− ), also referred to as -Sn. Our DFT + DMFT results indicate that -Sn is an ideal testing ground to explore electric field-driven orbital selectivity and Mott memory behavior, all arising from the close proximity of -Sn to metal insulator transitions. We discuss the relevance of orbital phase changes for -Sn in the context of the current–voltage ( ) characteristic for future silicon-based metal semiconductor atomristors.
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(This article belongs to the Section Condensed Matter Theory)
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Enhancing the Photoelectrochemical Performance of a Superlattice p–n Heterojunction CuFe2O4/ZnFe2O4 Electrode for Hydrogen Production
by
M. K. Al Turkestani
Condens. Matter 2024, 9(3), 31; https://doi.org/10.3390/condmat9030031 - 26 Jul 2024
Abstract
A p–n heterojunction film consisting of p-type CuFe2O4 and n-type ZnFe2O4 was fabricated in this study. The n-type ZnFe2O4 film was deposited on a stainless steel substrate using the spray pyrolysis method, after which
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A p–n heterojunction film consisting of p-type CuFe2O4 and n-type ZnFe2O4 was fabricated in this study. The n-type ZnFe2O4 film was deposited on a stainless steel substrate using the spray pyrolysis method, after which a top layer of p-type CuFe2O4 thin film was deposited and annealed. Characterization techniques, such as X-ray diffraction, scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy, and photoluminescence, confirmed the formation of a superlattice p–n heterojunction between CuFe2O4 and ZnFe2O4. Photoelectrochemical measurements were conducted to investigate the photoelectrochemical properties of the samples, resulting in a photocurrent of 1.2 mA/cm2 at 1.5 V (vs. Ag/AgCl) under illumination from a 100-watt LED light source. Utilizing the p–n junction of CuFe2O4/ZnFe2O4 as a photoanode increased the hydrogen production rate by 30% compared to that of the dark measurement. This enhancement in performance was attributed to the potential barrier at the p–n heterojunction interface, which improved the separation of photoinduced electron–hole pairs and facilitated a more efficient charge transfer. Additionally, coating the stainless steel electrode with this ferrite sample improved both the corrosion resistance and the stability of hydrogen production over extended operation times.
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(This article belongs to the Section Physics of Materials)
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The EuAPS Betatron Radiation Source: Status Update and Photon Science Perspectives
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Federico Galdenzi, Maria Pia Anania, Antonella Balerna, Richard J. Bean, Angelo Biagioni, Claudio Bortolin, Luca Brombal, Francesco Brun, Marcello Coreno, Gemma Costa, Lucio Crincoli, Alessandro Curcio, Martina Del Giorno, Enrico Di Pasquale, Gianluca di Raddo, Valentina Dompè, Sandro Donato, Zeinab Ebrahimpour, Antonio Falone, Andrea Frazzitta, Mario Galletti, Andrea Ghigo, Stefano Lauciani, Andrea Liedl, Valerio Lollo, Augusto Marcelli, Emiliano Principi, Andrea R. Rossi, Federica Stocchi, Fabio Villa, Marco Zottola, Alessandro Cianchi, Francesco Stellato and Massimo Ferrarioadd
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Condens. Matter 2024, 9(3), 30; https://doi.org/10.3390/condmat9030030 - 22 Jul 2024
Abstract
The EuPRAXIA EU project is at the forefront of advancing particle accelerator research and the development of photon sources through innovative plasma acceleration approaches. Within this framework, the EuAPS project aims to exploit laser wakefield acceleration to build and operate a betatron radiation
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The EuPRAXIA EU project is at the forefront of advancing particle accelerator research and the development of photon sources through innovative plasma acceleration approaches. Within this framework, the EuAPS project aims to exploit laser wakefield acceleration to build and operate a betatron radiation source at the INFN Frascati National Laboratory. The EuAPS source will provide femtosecond X-ray pulses in the spectral region between about 1 and 10 keV, unlocking a realm of experimental ultrafast methodologies encompassing diverse imaging and X-ray spectroscopy techniques. This paper presents a description of the EuAPS betatron source, including simulations of the photon beam parameters, outlines the preliminary design of the dedicated photon beamline, and provides an insightful overview of its photon science applications.
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(This article belongs to the Section Spectroscopy and Imaging in Condensed Matter)
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The Nature of Pointer States and Their Role in Macroscopic Quantum Coherence
by
Philip Turner and Laurent Nottale
Condens. Matter 2024, 9(3), 29; https://doi.org/10.3390/condmat9030029 - 17 Jul 2024
Abstract
This article begins with an interdisciplinary review of a hydrodynamic approach to understanding the origins and nature of macroscopic quantum phenomena in high-temperature superconductivity, superfluidity, turbulence and biological systems. Building on this review, we consider new theoretical insights into the origin and nature
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This article begins with an interdisciplinary review of a hydrodynamic approach to understanding the origins and nature of macroscopic quantum phenomena in high-temperature superconductivity, superfluidity, turbulence and biological systems. Building on this review, we consider new theoretical insights into the origin and nature of pointer states and their role in the emergence of quantum systems. The approach includes a theory of quantum coherence underpinned by turbulence, generated by a field of pointer states, which take the form of recirculating, spin-1/2 vortices (toroids), interconnected via a cascade of spin-1 vortices. Decoherence occurs when the bosonic network connecting pointer states is disrupted, leading to their localisation. Building further on this work, we explore how quantum particles (in the form of different vortex structures) could emerge as the product of a causal dynamic process, within a turbulent (fractal) spacetime. The resulting particle structures offer new insights into intrinsic spin, the probabilistic nature of the wave function and how we might consider pointer states within the standard “point source” representation of a quantum particle, which intuitively requires a more complexed description.
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(This article belongs to the Special Issue Feature Papers from Condensed Matter Editorial Board Members)
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The Multi-Detectors System of the PANDORA Facility: Focus on the Full-Field Pin-Hole CCD System for X-ray Imaging and Spectroscopy
by
David Mascali, Eugenia Naselli, Sandor Biri, Giorgio Finocchiaro, Alessio Galatà, Giorgio Sebastiano Mauro, Maria Mazzaglia, Bharat Mishra, Santi Passarello, Angelo Pidatella, Richard Rácz, Domenico Santonocito and Giuseppe Torrisi
Condens. Matter 2024, 9(2), 28; https://doi.org/10.3390/condmat9020028 - 20 Jun 2024
Abstract
PANDORA (Plasmas for Astrophysics Nuclear Decays Observation and Radiation for Archaeometry) is an INFN project aiming at measuring, for the first time, possible variations in in-plasma -decay lifetimes in isotopes of astrophysical interest as a function of thermodynamical conditions of the in-laboratory
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PANDORA (Plasmas for Astrophysics Nuclear Decays Observation and Radiation for Archaeometry) is an INFN project aiming at measuring, for the first time, possible variations in in-plasma -decay lifetimes in isotopes of astrophysical interest as a function of thermodynamical conditions of the in-laboratory controlled plasma environment. Theoretical predictions indicate that the ionization state can dramatically modify the -decay lifetime (even of several orders of magnitude). The PANDORA experimental approach consists of confining a plasma able to mimic specific stellar-like conditions and measuring the nuclear decay lifetime as a function of plasma parameters. The -decay events will be measured by detecting the -ray emitted by the daughter nuclei, using an array of 12 HPGe detectors placed around the magnetic trap. In this frame, plasma parameters have to be continuously monitored online. For this purpose, an innovative, non-invasive multi-diagnostic system, including high-resolution time- and space-resolved X-ray analysis, was developed, which will work synergically with the -rays detection system. In this contribution, we will describe this multi-diagnostics system with a focus on spatially resolved high-resolution X-ray spectroscopy. The latter is performed by a pin-hole X-ray camera setup operating in the 0.5–20 keV energy domain. The achieved spatial and energy resolutions are 450 µm and 230 eV at 8.1 keV, respectively. An analysis algorithm was specifically developed to obtain SPhC (Single Photon-Counted) images and local plasma emission spectrum in High-Dynamic-Range (HDR) mode. Thus, investigations of image regions where the emissivity can change by even orders of magnitude are now possible. Post-processing analysis is also able to remove readout noise, which is often observable and dominant at very low exposure times (ms). Several measurements have already been used in compact magnetic plasma traps, e.g., the ATOMKI ECRIS in Debrecen and the Flexible Plasma Trap at LNS. The main outcomes will be shortly presented. The collected data allowed for a quantitative and absolute evaluation of local emissivity, the elemental analysis, and the local evaluation of plasma density and temperature. This paper also discusses the new plasma emission models, implemented on PIC-ParticleInCell codes, which were developed to obtain powerful 3D maps of the X-rays emitted by the magnetically confined plasma. These data also support the evaluation procedure of spatially resolved plasma parameters from the experimental spectra as well as, in the near future, the development of appropriate algorithms for the tomographic reconstruction of plasma parameters in the X-ray domain. The described setups also include the most recent upgrade, consisting of the use of fast X-ray shutters with special triggering systems that will be routinely implemented to perform both space- and time-resolved spectroscopy during transient, stable, and turbulent plasma regimes (in the ms timescale).
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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Microstructure and Unusual Ferromagnetism of Epitaxial SnO2 Films Heavily Implanted with Co Ions
by
Rustam I. Khaibullin, Amir I. Gumarov, Iskander R. Vakhitov, Andrey A. Sukhanov, Nikolay M. Lyadov, Airat G. Kiiamov, Dilyara M. Kuzina, Valery V. Bazarov and Almaz L. Zinnatullin
Condens. Matter 2024, 9(2), 27; https://doi.org/10.3390/condmat9020027 - 11 Jun 2024
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In this work, we have studied the microstructure and unusual ferromagnetic behavior in epitaxial tin dioxide (SnO2) films implanted with 40 keV Co+ ions to a high fluence of 1.0 × 1017 ions/cm2 at room or elevated substrate
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In this work, we have studied the microstructure and unusual ferromagnetic behavior in epitaxial tin dioxide (SnO2) films implanted with 40 keV Co+ ions to a high fluence of 1.0 × 1017 ions/cm2 at room or elevated substrate temperatures. The aim was to comprehensively understand the interplay between cobalt implant distribution, crystal defects (such as oxygen vacancies), and magnetic properties of Co-implanted SnO2 films, which have potential applications in spintronics. We have utilized scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), differential thermomagnetic analysis (DTMA), and ferromagnetic resonance (FMR) to investigate Co-implanted epitaxial SnO2 films. The comprehensive experimental investigation shows that the Co ion implantation with high cobalt concentration induces significant changes in the microstructure of SnO2 films, leading to the appearance of ferromagnetism with the Curie temperature significantly above the room temperature. We also established a strong influence of implantation temperature and subsequent high-temperature annealing in air or under vacuum on the magnetic properties of Co-implanted SnO2 films. In addition, we report a strong chemical effect of ethanol on the FMR spectra. The obtained results are discussed within the model of two magnetic layers, with different concentrations and valence states of the implanted cobalt, and with a high content of oxygen vacancies.
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Open AccessEditor’s ChoiceArticle
Enhancing Spectroscopic Experiment Calibration through Differentiable Programming
by
Fabrizio Napolitano
Condens. Matter 2024, 9(2), 26; https://doi.org/10.3390/condmat9020026 - 5 Jun 2024
Abstract
In this work, we present an innovative calibration technique leveraging differentiable programming to enhance energy resolution and reduce the energy scale systematic uncertainty in X-ray spectroscopic experiments. This approach is demonstrated using synthetic data and is applicable in general to various spectroscopic measurements.
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In this work, we present an innovative calibration technique leveraging differentiable programming to enhance energy resolution and reduce the energy scale systematic uncertainty in X-ray spectroscopic experiments. This approach is demonstrated using synthetic data and is applicable in general to various spectroscopic measurements. This method extends the scope of differentiable programming for calibration, employing Kernel Density Estimation (KDE) to achieve a target Probability Density Function (PDF) for a fully differentiable model of the calibration. To assess the effectiveness of the calibration, we conduct a toy simulation replicating the entire detector response chain and compare it with a standard calibration. This ensures a robust and reliable calibration methodology, holding promise for improving energy resolution and providing a more versatile and efficient approach without the need for extensive fine-tuning.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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The Effective Potential of Scalar Pseudo-Quantum Electrodynamics in (2 + 1)D
by
Leandro O. Nascimento, Carlos A. P. C. Junior and José R. Santos
Condens. Matter 2024, 9(2), 25; https://doi.org/10.3390/condmat9020025 - 30 May 2024
Abstract
The description of the electron–electron interactions in two-dimensional materials has a dimensional mismatch, where electrons live in (2 + 1)D while photons propagate in (3 + 1)D. In order to define an action in (2 + 1)D, one may perform a dimensional reduction
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The description of the electron–electron interactions in two-dimensional materials has a dimensional mismatch, where electrons live in (2 + 1)D while photons propagate in (3 + 1)D. In order to define an action in (2 + 1)D, one may perform a dimensional reduction of quantum electrodynamics in (3 + 1)D (QED4) into pseudo-quantum electrodynamics (PQED). The main difference between this model and QED4 is the presence of a pseudo-differential operator in the Maxwell term. However, besides the Coulomb repulsion, electrons in a material are subjected to several microscopic interactions, which are inherent in a many-body system. These are expected to reduce the range of the Coulomb potential, leading to a short-range interaction. Here, we consider the coupling to a scalar field in PQED for explaining such a mechanism, which resembles the spontaneous symmetry breaking (SSB) in Abelian gauge theories. In order to do so, we consider two cases: (i) by coupling the quantum electrodynamics to a Higgs field in (3 + 1)D and, thereafter, performing the dimensional reduction; and (ii) by coupling a Higgs field to the gauge field in PQED and, subsequently, calculating its effective potential. In case (i), we obtain a model describing electrons interacting through the Yukawa potential and, in case (ii), we show that SSB does not occur at one-loop approximation. The relevance of the model for describing electronic interactions in two-dimensional materials is also addressed.
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(This article belongs to the Special Issue PQED: 30 Years of Reduced Quantum Electrodynamics)
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Open AccessEditorial
Meeting and Working with K. Alex Müller: Personal Memories
by
Annette Bussmann-Holder and Hugo Keller
Condens. Matter 2024, 9(2), 24; https://doi.org/10.3390/condmat9020024 - 8 May 2024
Abstract
On 9 January 2023, K [...]
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(This article belongs to the Special Issue Complexity in Quantum Materials: In Honor of Prof. K.A. Muller)
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Alex’s Vision in Functional Quantum Matter
by
Davor Pavuna
Condens. Matter 2024, 9(2), 23; https://doi.org/10.3390/condmat9020023 - 18 Apr 2024
Abstract
My ‘In Memoriam’ contribution is very personal, as it includes many human and professional insights that I received from Alex Müller himself [...]
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(This article belongs to the Special Issue Complexity in Quantum Materials: In Honor of Prof. K.A. Muller)
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Open AccessFeature PaperArticle
Optimization of a BEGe Detector Setup for Testing Quantum Foundations in the Underground LNGS Laboratory
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Kristian Piscicchia, Alberto Clozza, Diana Laura Sirghi, Massimiliano Bazzi, Nicola Bortolotti, Mario Bragadireanu, Michael Cargnelli, Luca De Paolis, Raffaele Del Grande, Carlo Guaraldo, Mihail Iliescu, Matthias Laubenstein, Simone Manti, Johann Marton, Marco Miliucci, Fabrizio Napolitano, Alessio Porcelli, Alessandro Scordo, Francesco Sgaramella, Florin Sirghi, Sandro Tomassini, Oton Vazquez Doce, Johann Zmeskal and Catalina Curceanuadd
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Condens. Matter 2024, 9(2), 22; https://doi.org/10.3390/condmat9020022 - 11 Apr 2024
Abstract
In this work, we report on tests performed with an experimental apparatus prototype based on a broad-energy germanium detector aimed at investigating topical, foundational issues in quantum mechanics: i.e., possible violations of the spin-statistics connection and models of dynamical wave function collapse. Our
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In this work, we report on tests performed with an experimental apparatus prototype based on a broad-energy germanium detector aimed at investigating topical, foundational issues in quantum mechanics: i.e., possible violations of the spin-statistics connection and models of dynamical wave function collapse. Our recent phenomenological analyses demonstrated the importance of pushing the research of new physics signal, predicted in these fields, to an energy range below 10 keV. We describe the development of the dedicated data acquisition system and of the pulse shape discrimination algorithm, which have already allowed us to get a factor two improvement in the lower energy threshold. Future plans are discussed to further improve the lower energy threshold to the level of a few keV.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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Open AccessReview
Superconductors without Symmetry Breaking
by
Maria Cristina Diamantini
Condens. Matter 2024, 9(2), 21; https://doi.org/10.3390/condmat9020021 - 2 Apr 2024
Abstract
We review the main features of type-III superconductivity. This is a new type of superconductivity that exists in both 2 and 3 spatial dimensions. The main characteristics are emergent granularity and the superconducting gap being opened by a topological mechanism, with no Higgs
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We review the main features of type-III superconductivity. This is a new type of superconductivity that exists in both 2 and 3 spatial dimensions. The main characteristics are emergent granularity and the superconducting gap being opened by a topological mechanism, with no Higgs field involved. Superconductivity is destroyed by the proliferation of vortices and not by the breaking of Cooper pairs, which survive above the critical temperature. The hallmark of this superconductivity mechanism, in 3 spatial dimensions (3D), is the Vogel–Fulcher–Taman scaling of the resistance with temperature.
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(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)
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Topological Phase Diagram of an Interacting Kitaev Chain: Mean Field versus DMRG Study
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Giovanni Nunziante, Alfonso Maiellaro, Claudio Guarcello and Roberta Citro
Condens. Matter 2024, 9(1), 20; https://doi.org/10.3390/condmat9010020 - 20 Mar 2024
Abstract
In this work, we study the topological phase transitions of a Kitaev chain generalized by the addition of nearest-neighbor Coulomb interaction. We show the presence of a robust topological phase as a function of the interaction strength and of the on-site energy with
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In this work, we study the topological phase transitions of a Kitaev chain generalized by the addition of nearest-neighbor Coulomb interaction. We show the presence of a robust topological phase as a function of the interaction strength and of the on-site energy with associated non-zero energy Majorana states localized at the chain edges. We provide an effective mean-field model that allows for the self-consistent computation of the mean value of the local particle number operator, and we also perform Density Matrix Renormalization Group numerical simulations based on a tensor network approach. We find that the two methods show a good agreement in reporting the phase transition between trivial and topological superconductivity. Temperature robustness within a physically relevant threshold has also been demonstrated. These findings shed light on an entire class of topological interacting one-dimensional systems in which the effects of residual Coulomb interactions play a relevant role.
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(This article belongs to the Special Issue Multicomponent Superconductivity and Superfluidity)
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Condensed Matter
Complexity in Quantum Materials: In Honor of Prof. K.A. Muller
Guest Editors: Antonio Bianconi, Annette Bussmann-HolderDeadline: 31 October 2024
Special Issue in
Condensed Matter
Fluctuations and Highly Non-linear Phenomena in Superfluids and Superconductors VIII
Guest Editors: Luca Dell'Anna, Luca Salasnich, Roberta Citro, Claudio Guarcello, Andrea PeraliDeadline: 30 November 2024
Special Issue in
Condensed Matter
Superstripes Physics, 3rd Edition
Guest Editors: Antonio Bianconi, Yasutomo UemuraDeadline: 30 November 2024
Special Issue in
Condensed Matter
Selected Papers from the International Conference on Quantum Materials and Technologies (ICQMT2024)
Guest Editors: Valerii Vinokur, Ali Gencer, Annette Bussmann-Holder, J. Javier Campo RuizDeadline: 15 December 2024