Condensed Matter

18 pages, 23429 KiB

Open AccessArticle

Synthesis of PTh/PEDOT Films into FTO Substrate by Electrodeposition, for Energy Storage Systems

by Daniel Alejandro Vázquez-Loredo, Ulises Páramo-García, Luis Alejandro Macclesh Del Pino-Pérez, Nohra Violeta Gallardo-Rivas, Ricardo García-Alamilla and Diana Lucia Campa-Guevara

Condens. Matter 2025, 10(2), 26; https://doi.org/10.3390/condmat10020026 - 27 Apr 2025

Abstract

Thin films of monomeric species polythiophene (PTh), poly-(3,4-ethylenedioxythiophene) (PEDOT), and the copolymer PTh/PEDOT were prepared through electropolymerization and deposited above fluorine-doped tin oxide (FTO) substrates. The functional groups of the monomeric species (PTh, PEDOT) and polymeric species (PTh/PEDOT) were characterized by Fourier-transform infrared [...] Read more.

Thin films of monomeric species polythiophene (PTh), poly-(3,4-ethylenedioxythiophene) (PEDOT), and the copolymer PTh/PEDOT were prepared through electropolymerization and deposited above fluorine-doped tin oxide (FTO) substrates. The functional groups of the monomeric species (PTh, PEDOT) and polymeric species (PTh/PEDOT) were characterized by Fourier-transform infrared spectroscopy, while morphological properties were evaluated using scanning electron microscopy, optical microscopy, and atomic force microscopy. The analysis showed that monomers films exhibited less material deposition; otherwise, the copolymer PTh/PEDOT showed better deposition on substrate. In addition, the electrochemical characterization showed that the materials that resulted from copolymerization presented an improvement in electrochemical properties relating to monomer properties. The effect of overoxidation of the monomers applied during the electropolymerization process is also known. Full article

(This article belongs to the Section Surface and Interfaces)

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3 pages, 145 KiB

Open AccessEditorial

Novel Radiation Facilities Based on Plasma Acceleration: The Future of Free Electron Lasers

by Marcello Coreno, Massimo Ferrario, Augusto Marcelli and Francesco Stellato

Condens. Matter 2025, 10(2), 25; https://doi.org/10.3390/condmat10020025 - 27 Apr 2025

Abstract

Exploiting acceleration gradients that are up to three orders of magnitude higher than those achievable using conventional radiofrequency-based devices, plasma-based devices promise a revolution in particle acceleration, enabling particles to reach high energies over much shorter distances than existing accelerators [...] Full article

(This article belongs to the Special Issue Experimental Ideas for Novel FEL Facilities Based on Plasma Acceleration)

3 pages, 123 KiB

Open AccessEditorial

In-Depth Experimental and Computational Studies on Rechargeable Battery Materials

by Jan Kuriplach and Rolando Saniz

Condens. Matter 2025, 10(2), 24; https://doi.org/10.3390/condmat10020024 - 25 Apr 2025

Abstract

Judging by the number of downloads and citations, the topics covered by the Special Issue “Rechargeable Batteries Studied Using Advanced Spectroscopic and Computational Techniques I” [...] Full article

(This article belongs to the Special Issue Rechargeable Batteries Studied Using Advanced Spectroscopic and Computational Techniques II)

8 pages, 512 KiB

Open AccessArticle

Energy Structure of Yb³⁺-Yb³⁺ Paired Center in LiNbO₃ Crystal

by Gagik Demirkhanyan, Narine Babajanyan, Ninel Kokanyan, Michel Aillerie, Marco Bazzan and Edvard Kokanyan

Condens. Matter 2025, 10(2), 23; https://doi.org/10.3390/condmat10020023 - 25 Apr 2025

Abstract

Within the framework of Dexter’s theory, we calculate the energies of the Stark levels of Yb³⁺-Yb³⁺ paired centers in lithium niobate doped with Yb³⁺ ions (LiNbO₃:Yb³⁺) crystal, considering the interaction of optical electrons of ytterbium [...] Read more.

Within the framework of Dexter’s theory, we calculate the energies of the Stark levels of Yb³⁺-Yb³⁺ paired centers in lithium niobate doped with Yb³⁺ ions (LiNbO₃:Yb³⁺) crystal, considering the interaction of optical electrons of ytterbium ions forming the paired center. The calculated Stark level energies are shown to correspond well with the observed cooperative luminescence wavelengths. Full article

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24 pages, 3710 KiB

Open AccessReview

The Laser Powder Bed Fusion of Nd₂Fe₁₄B Permanent Magnets: The State of the Art

by Ivan Pelevin, Maria Lyange, Leonid Fedorenko, Stanislav Chernyshikhin and Irina Tereshina

Condens. Matter 2025, 10(2), 22; https://doi.org/10.3390/condmat10020022 - 24 Apr 2025

Abstract

In recent years, significant effort was made to make the 3D printing of fully dense rare-earth permanent magnets a reality. Since suitable Nd₂Fe₁₄B-based initial powder material became available, additive manufacturing implementation spread widely, which led to many studies being [...] Read more.

In recent years, significant effort was made to make the 3D printing of fully dense rare-earth permanent magnets a reality. Since suitable Nd₂Fe₁₄B-based initial powder material became available, additive manufacturing implementation spread widely, which led to many studies being focused on using this material in 3D printing. This study shows the principal possibilities of the synthesis of Nd-Fe-B magnets by means of the laser powder bed fusion technique; moreover, this study shows significant progress in increasing their magnetic properties. This progress was made possible by different approaches, such as 3D-printing process optimization, the addition of a second phase (a low-melting eutectic) into the initial powder, the tuning of the main phase’s composition, and exploring different scanning strategies. However, the current level of material magnetic properties obtained via laser powder bed fusion is still far from that of magnets produced by using conventional powder metallurgy methods. The present review aims to capture the current state-of-the-art trials and highlight the main challenges. Full article

(This article belongs to the Section Magnetism)

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29 pages, 10332 KiB

Open AccessReview

Basic Aspects of Ferroelectricity Induced by Noncollinear Alignment of Spins

by I. V. Solovyev

Condens. Matter 2025, 10(2), 21; https://doi.org/10.3390/condmat10020021 - 11 Apr 2025

Abstract

Basic principles of ferroelectric activity induced by the noncollinear alignment of spins are reviewed. There is a fundamental reason why the inversion symmetry can be broken by certain magnetic order. This situation occurs when the magnetic order simultaneously involves ferromagnetic (

F

) [...] Read more.

Basic principles of ferroelectric activity induced by the noncollinear alignment of spins are reviewed. There is a fundamental reason why the inversion symmetry can be broken by certain magnetic order. This situation occurs when the magnetic order simultaneously involves ferromagnetic (

F

) and antiferromagnetic (

A

) counterparts, transforming under the spatial inversion

I

and time reversal

T

as

I F = F

and

IT A = A

, respectively. The incompatibility of these two conditions results in breaking the inversion symmetry, which manifests itself in the electric polarization

\vec{P}

. The noncollinear alignment of spins is one of examples of such coexistence of

F

and

A

. This coexistence principle imposes a constraint on possible dependencies of

\vec{P}

on the directions of spins, which can include only “antisymmetric coupling” in the bond,

{\vec{P}}_{i j} \cdot [e_{i} \times e_{j}]

, and “single-ion anisotropy”,

e_{i} \cdot

\vec{Π}

e_{i}

. Microscopically,

{\vec{P}}_{i j}

can be evaluated in the framework of superexchange theory. For the single Kramers doublet, this theory yields

{\vec{P}}_{i j} \sim {\vec{r}}_{i j}^{}

, where

{\vec{r}}_{i j}^{}

is the spin-dependent part of the position operator induced by the relativistic spin-orbit coupling.

{\vec{r}}_{i j}^{}

remains invariant under spatial inversion, providing the microscopic reason why noncollinear alignment of spins can induce

\vec{P}

even in centrosymmetric crystals. The symmetry properties of

{\vec{r}}_{i j}^{}

can be rationalized from the viewpoint of symmetry of Kramers states. Particularly, the commonly used Katsura–Nagaosa–Balatsky (KNB) rule

\vec{P} \propto {\vec{ϵ}}_{j i} \times [e_{i} \times e_{j}]

(

{\vec{ϵ}}_{j i}

being the direction of the bond

i j

) can be justified only for relatively high symmetry of the bonds. The single-ion anisotropy vanishes for the spin

\frac{1}{2}

or if magnetic ions are located in inversion centers, thus severely restricting the applicability of this microscopic mechanism. The properties of multiferroic materials are reconsidered from the viewpoint of these principles. A particular attention is paid to complications caused by possible deviations from the KNB rule. Full article

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14 pages, 991 KiB

Open AccessReview

Emergent Magnetic Monopoles in Quantum Matter

by Maria Cristina Diamantini

Condens. Matter 2025, 10(2), 20; https://doi.org/10.3390/condmat10020020 - 1 Apr 2025

Abstract

Magnetic monopoles, though elusive as elementary particles, emerge as quantum excitations in granular quantum materials. Under certain conditions, they can undergo Bose condensation, leading to the formation of a novel state of matter known as the superinsulator. In this state, charge carriers, Cooper [...] Read more.

Magnetic monopoles, though elusive as elementary particles, emerge as quantum excitations in granular quantum materials. Under certain conditions, they can undergo Bose condensation, leading to the formation of a novel state of matter known as the superinsulator. In this state, charge carriers, Cooper pairs and anti-Cooper pairs, are bound together by an electric flux string, forming neutral electric pions. This confinement mechanism results in an infinite resistance that persists even at finite temperatures. Superinsulators behave, thus, as dual superconductors. Full article

(This article belongs to the Special Issue Superstripes Physics, 3rd Edition)

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16 pages, 5365 KiB

Open AccessArticle

Kinetics of Thickness Growth of Silicon Films During Pulsed Magnetron Sputtering Using the Caroline D12C System

by Kanat Tolubayev, Bakhyt Zhautikov, Nikolay Zobnin, Guldana Dairbekova and Saule Kabiyeva

Condens. Matter 2025, 10(1), 19; https://doi.org/10.3390/condmat10010019 - 20 Mar 2025

Abstract

In this study, the effects of specific power (1–100 W/cm²), operating pressure (0.5–3.0 Pa), and voltage frequency (20–500 kHz) on film growth kinetics, morphology, and silicon entrainment were investigated to optimize magnetron sputtering for producing thin silicon films suitable for lithium-ion [...] Read more.

In this study, the effects of specific power (1–100 W/cm²), operating pressure (0.5–3.0 Pa), and voltage frequency (20–500 kHz) on film growth kinetics, morphology, and silicon entrainment were investigated to optimize magnetron sputtering for producing thin silicon films suitable for lithium-ion battery anodes. Silicon films were deposited on copper substrates using the Caroline D12C system. The film thickness and morphology were determined using scanning electron microscopy and atomic force microscopy. It was found that the porosity of the films increases with increasing pressure in the working chamber. It was found that the film morphology is non-uniform up to a thickness of 100–150 nm. After that, the film thickness becomes uniform over the entire substrate surface, and the deposition rate increases sharply, i.e., an induction period is observed. The induction period duration decreases with increasing voltage power and frequency. At the same time, silicon removal increases. Frequency has a greater effect on both parameters. The paper specifies a strategy for the technical and economic optimization of the magnetron sputtering process, which determines a compromise between the positive effect of increasing productivity and the negative effect of silicon removal. Full article

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11 pages, 415 KiB

Open AccessArticle

Orbital-Nematic and Two-Fluid Superconductivity in Hole-Doped NdNiO₂

by Luis Craco

Condens. Matter 2025, 10(1), 18; https://doi.org/10.3390/condmat10010018 - 14 Mar 2025

Abstract

Based on DFT + DMFT, we investigate the orbital-nematic and s-wave superconducting states of a hole-doped

{NdNiO}_{2}

superconductor. We emphasize the role played by the interorbital proximity effect in determining the orbital-selective electronic state both in the normal and superconducting phases. [...] Read more.

Based on DFT + DMFT, we investigate the orbital-nematic and s-wave superconducting states of a hole-doped

{NdNiO}_{2}

superconductor. We emphasize the role played by the interorbital proximity effect in determining the orbital-selective electronic state both in the normal and superconducting phases. Specifically, we show how orbital-nematic plus s-wave pairing symmetry acting on the

x z

orbital might have pronounced effects on proximitized non-superconducting Ni-

3 d

orbitals due to many-particle electron–electron interactions. This work represents a step forward in understanding the emergence of two-fluid superconductivity (with superconducting

x z

and non-superconducting

x y, y z, x^{2} - y^{2}, 3 z^{2} - r^{2}

channels) in hole-doped

{NdNiO}_{2}

superconductors. Full article

(This article belongs to the Special Issue Complexity in Quantum Materials: In Honor of Prof. K.A. Muller)

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9 pages, 1767 KiB

Open AccessArticle

Possible Superconductivity in Very Thin Magnesium Films

by Giovanni Alberto Ummarino and Alessio Zaccone

Condens. Matter 2025, 10(1), 17; https://doi.org/10.3390/condmat10010017 - 10 Mar 2025

Abstract

It is known that noble metals such as gold, silver and copper are not superconductors; this is also true for magnesium. This is due to the weakness of the electron–phonon interaction, which makes them excellent conductors but not superconductors. As has recently been [...] Read more.

It is known that noble metals such as gold, silver and copper are not superconductors; this is also true for magnesium. This is due to the weakness of the electron–phonon interaction, which makes them excellent conductors but not superconductors. As has recently been shown for gold, silver and copper, and even for magnesium, it is possible that in very particular situations, superconductivity may occur. Quantum confinement in thin films has been consistently shown to induce a significant enhancement of the superconducting critical temperature in several superconductors. It is therefore an important fundamental question whether ultra-thin film confinement may induce observable superconductivity in non-superconducting metals such as magnesium. We study this problem using a generalization, in the Eliashberg framework, of a BCS theory of superconductivity in good metals under thin-film confinement. By numerically solving these new Eliashberg-type equations, we find the dependence of the superconducting critical temperature on the film thickness, L. This parameter-free theory predicts superconductivity in very thin magnesium films. We demonstrate that this is a fine-tuning problem where the thickness must assume a very precise value, close to half a nanometer. Full article

(This article belongs to the Special Issue Superstripes Physics, 3rd Edition)

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4 pages, 167 KiB

Open AccessEditorial

High-Precision X-Ray Measurements 2023

by Fabrizio Napolitano and Alessandro Scordo

Condens. Matter 2025, 10(1), 16; https://doi.org/10.3390/condmat10010016 - 6 Mar 2025

Abstract

High-Precision X-ray Measurements 2023 is a Special Issue of the journal Condensed Matter enclosing the scientific content of the 2023 High-Precision X-ray Measurements (HPXRM) conference [...] Full article

(This article belongs to the Special Issue High Precision X-ray Measurements 2023)

18 pages, 1106 KiB

Open AccessArticle

Edelstein Effect in Isotropic and Anisotropic Rashba Models

by Irene Gaiardoni, Mattia Trama, Alfonso Maiellaro, Claudio Guarcello, Francesco Romeo and Roberta Citro

Condens. Matter 2025, 10(1), 15; https://doi.org/10.3390/condmat10010015 - 4 Mar 2025

Abstract

We investigate spin-to-charge conversion via the Edelstein effect in a 2D Rashba electron gas using the semiclassical Boltzmann approach. We analyze the magnetization arising from the direct Edelstein effect, taking into account an anisotropic Rashba model. We study how this effect depends on [...] Read more.

We investigate spin-to-charge conversion via the Edelstein effect in a 2D Rashba electron gas using the semiclassical Boltzmann approach. We analyze the magnetization arising from the direct Edelstein effect, taking into account an anisotropic Rashba model. We study how this effect depends on the effective masses and Rashba spin–orbit coupling parameters, extracting analytical expressions for the high electronic density regime. Indeed, it is possible to manipulate the anisotropy introduced into the system through these parameters to achieve a boost in the Edelstein response compared to the isotropic Rashba model. We also discuss the theoretical framework to study the inverse Edelstein effect and calculate self-consistently the electric current induced by the proximity of the system to a ferromagnet. These results provide insights into the role of Rashba spin–orbit coupling and anisotropic effects in spin–charge conversion phenomena. Full article

(This article belongs to the Special Issue Fluctuations and Highly Non-linear Phenomena in Superfluids and Superconductors VIII)

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11 pages, 480 KiB

Open AccessArticle

Electron Density and Compressibility in the Kitaev Model with a Spatially Modulated Phase in the Superconducting Pairing

by Fabián G. Medina Cuy and Fabrizio Dolcini

Condens. Matter 2025, 10(1), 14; https://doi.org/10.3390/condmat10010014 - 28 Feb 2025

Abstract

A current flowing through a one-dimensional Kitaev chain induces a spatial modulation in its superconducting pairing, characterized by a wavevector Q, which is known to induce two types of topological phase transitions: one is the customary band topology transition between gapped phases, [...] Read more.

A current flowing through a one-dimensional Kitaev chain induces a spatial modulation in its superconducting pairing, characterized by a wavevector Q, which is known to induce two types of topological phase transitions: one is the customary band topology transition between gapped phases, while the other is a Lifshitz transition related to the Fermi surface topology and leading to a gapless superconducting phase. We investigate the behavior of the electron density

ρ

and the compressibility

κ

across the two types of transitions, as a function of the model parameters. We find that the behavior of

ρ

as a function of Q and chemical potential

μ

enables one to infer the ground state phase diagram. Moreover, the analysis of the compressibility

κ

as a function of

μ

enables one to distinguish the two transitions: While

κ

exhibits a symmetric divergence across the band topology transition, it displays an asymmetric jump across the Lifshitz transition. Full article

(This article belongs to the Special Issue Fluctuations and Highly Non-linear Phenomena in Superfluids and Superconductors VIII)

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16 pages, 2650 KiB

Open AccessReview

On a Crystal Chemical Vision on Niobium-Based Superconducting Intermetallics: A Brief Overview

by Taimo Priinits, Artjom Vargunin and Aleksandr Liivand

Condens. Matter 2025, 10(1), 13; https://doi.org/10.3390/condmat10010013 - 14 Feb 2025

Abstract

The present report focuses on the close interplay between condensed matter physics and solid-state chemistry in Nb-based binary intermetallic compounds. Over the recent four decades, these materials have been widely used in the development of a number of superconducting applications and various superconducting [...] Read more.

The present report focuses on the close interplay between condensed matter physics and solid-state chemistry in Nb-based binary intermetallic compounds. Over the recent four decades, these materials have been widely used in the development of a number of superconducting applications and various superconducting devices, including non-standard engineering solutions in the design of large magnets. However, since the 1980s, when it became apparent that the mechanical and superior superconducting properties of ordered intermetallic alloys such as Nb₃Sn were largely due to their unique structural features, much of the research interest in the science of superconducting intermetallic alloys has been redirected to the development of necessary engineering applications in high magnetic field technology. Accordingly, the important role of crystal chemistry in understanding the fundamental aspects of the material properties of the Nb₃Sn family of intermetallics has not been extensively explored. In this paper, we try to fill this gap by investigating the relationships between composition, microstructure and properties, highlighting their relevance to technological applications. Our goal is to combine aspects of crystal chemistry with physical and material application issues. We shed light on the atomic assembly mechanisms and processes in terms of changes in the chemical environment, lattice structure, crystallization pathway, and macroscale phase textures, which can help in interpreting and explaining the prospects and limitations of the superconducting properties of Nb₃Sn. In the context of past and present prospects and limitations, we briefly overview most important technological applications and discuss the various inter-relations between superconductivity and structural properties of Nb-based A-15 intermetallic alloys. We argue that these inter-relations can be used to find Nb-based superconductors with more superior properties and stronger technological usability. Full article

(This article belongs to the Section Superconductivity)

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13 pages, 17818 KiB

Open AccessArticle

Optical Mapping and On-Demand Selection of Local Hysteresis Properties in VO₂

by Melissa Alzate Banguero, Sayan Basak, Nicolas Raymond, Forrest Simmons, Pavel Salev, Ivan K. Schuller, Lionel Aigouy, Erica W. Carlson and Alexandre Zimmers

Condens. Matter 2025, 10(1), 12; https://doi.org/10.3390/condmat10010012 - 13 Feb 2025

Abstract

Quantum materials have tremendous potential for disruptive applications. However, scaling devices down has been challenging due to electronic inhomogeneities in many of these materials. Understanding and controlling these electronic patterns on a local scale has thus become crucial to further new applications. To [...] Read more.

Quantum materials have tremendous potential for disruptive applications. However, scaling devices down has been challenging due to electronic inhomogeneities in many of these materials. Understanding and controlling these electronic patterns on a local scale has thus become crucial to further new applications. To address this issue, we have developed a new optical microscopy method that allows for the precise quasi-continuous filming of the insulator-to-metal transition in VO

_{2}

with fine temperature steps. This enables us to track metal and insulator domains over thousands of images and quantify, for the first time, the local hysteresis properties of VO

_{2}

thin films. The analysis of the maps has allowed us to quantify cycle-to-cycle reproducibility of the local transitions and reveals a positive correlation between the local insulator–metal transition temperatures T

_{c}

and the local hysteresis widths

Δ T_{c}

. These maps also enable the optical selection of regions of high or low transition temperature in combination with large or nearly absent local hysteresis. These maps pave the way to understand and use stochasticity to advantage in these materials by picking on-demand transition properties, allowing the scaling down of devices such as optical switches, infrared microbolometers and spiking neural networks. Full article

(This article belongs to the Special Issue Superstripes Physics, 3rd Edition)

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18 pages, 1287 KiB

Open AccessArticle

Inhomogeneous Evolution of a Dense Ensemble of Optically Pumped Excitons to a Charge Transfer State

by Natasha Kirova and Serguei Brazovskii

Condens. Matter 2025, 10(1), 11; https://doi.org/10.3390/condmat10010011 - 9 Feb 2025

Abstract

Phase transformations induced by short optical pulses are mainstream in studies on the dynamics of cooperative electronic states. We present a semiphenomenological modeling of spatiotemporal effects expected when optical excitons are intricate with the order parameter such as in, e.g., organic compounds with [...] Read more.

Phase transformations induced by short optical pulses are mainstream in studies on the dynamics of cooperative electronic states. We present a semiphenomenological modeling of spatiotemporal effects expected when optical excitons are intricate with the order parameter such as in, e.g., organic compounds with neutral-ionic ferroelectric phase transitions. A conceptual complication appears here, where both the excitation and the ground state ordering are built from the intermolecular electronic transfer. To describe both thermodynamic and dynamic effects on the same root, we adopt, for the phase transition, a view of the excitonic insulator—a hypothetical phase of a semiconductor that appears if the exciton energy becomes negative. After the initial pumping pulse, a quasi-condensate of excitons can appear as a macroscopic quantum state that then evolves, while interacting with other degrees of freedom which are prone to an instability. The self-trapping of excitons enhances their density, which can locally surpass a critical value to trigger the phase transformation. The system is stratified in domains that evolve through dynamical phase transitions and may persist even after the initiating excitons have recombined. Full article

(This article belongs to the Special Issue Superstripes Physics, 3rd Edition)

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19 pages, 386 KiB

Open AccessArticle

Strained Graphene as Pristine Graphene with a Deformed Momentum Operator

by David Valenzuela, Alfredo Raya and Juan D. García-Muñoz

Condens. Matter 2025, 10(1), 10; https://doi.org/10.3390/condmat10010010 - 7 Feb 2025

Abstract

We explore the equivalence between the low-energy dynamics of strained graphene and a quantum mechanical framework for the 2D Dirac equation in flat space with a deformed momentum operator. By considering some common forms of the anisotropic Fermi velocity tensor emerging from the [...] Read more.

We explore the equivalence between the low-energy dynamics of strained graphene and a quantum mechanical framework for the 2D Dirac equation in flat space with a deformed momentum operator. By considering some common forms of the anisotropic Fermi velocity tensor emerging from the elasticity theory, we associate such tensor forms with a deformation of the momentum operator. We first explore the bound states of charge carriers in a background uniform magnetic field in this framework and quantify the impact of strain in the energy spectrum. Then, we use a quadrature algebra formula as a mathematical tool to analyze the impact of the deformation attached to the momentum operator and identify physical consequences of such deformation in terms of energy modifications due to the applied strain. Full article

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10 pages, 349 KiB

Open AccessFeature PaperArticle

Temperature Dependence of the Dynamical and DC Conductivity in 2D Dirac Systems: Self-Consistent Random-Phase-Approximation Approach

by Ivan Kupčić and Patrik Papac

Condens. Matter 2025, 10(1), 9; https://doi.org/10.3390/condmat10010009 - 1 Feb 2025

Abstract

We studied relaxation processes in heavily doped two-dimensional Dirac systems associated with electron scattering by acoustic and optical phonons and by static disorder. The frequency dependence of the real and imaginary parts of the relaxation function is calculated for different temperatures. The two-component [...] Read more.

We studied relaxation processes in heavily doped two-dimensional Dirac systems associated with electron scattering by acoustic and optical phonons and by static disorder. The frequency dependence of the real and imaginary parts of the relaxation function is calculated for different temperatures. The two-component low-frequency dynamical conductivity is found to be strongly dependent on temperature. At low temperatures, the imaginary part of the zero-frequency relaxation function and the DC resistivity are characterized by the scaling law

a T^{x}

with the exponent x between 2.5 and 3. Full article

(This article belongs to the Special Issue Selected Papers from the International Conference on Quantum Materials and Technologies (ICQMT2024))

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11 pages, 5696 KiB

Open AccessArticle

Structure and Properties of (Fe₈₀Ga₂₀)_99.8Ce_0.2 Alloy in Cast and Hot Rolled State

by Vasily Milyutin, Irina Gervasyeva, Azambek Kalonov, Denis Shishkin, Denis Davydov and Liudmila Stashkova

Condens. Matter 2025, 10(1), 8; https://doi.org/10.3390/condmat10010008 - 30 Jan 2025

Abstract

FeGa alloys with small additions of rare-earth elements surpass binary alloys in magnetostriction and plasticity. For this reason, they are considered promising magnetostrictive materials for various electrical engineering applications. The alloy (Fe₈₁Ga₁₉)_99.8Ce_0.2 was prepared and investigated [...] Read more.

FeGa alloys with small additions of rare-earth elements surpass binary alloys in magnetostriction and plasticity. For this reason, they are considered promising magnetostrictive materials for various electrical engineering applications. The alloy (Fe₈₁Ga₁₉)_99.8Ce_0.2 was prepared and investigated in this work. It was found that in the cast state, it has a magnetostriction of 3/2 λ about 100 ppm, saturation magnetization of 150 emu/g, tensile strength of about 300 MPa, and fracture strain of 3%. The microstructure, crystallographic texture, and behavior when heated of the alloy were investigated. Then the ingot was subjected to forging and hot rolling with a deformation degree of 90% at 1000 °C. The structure and mechanical properties of samples cut from a hot rolling sheet were studied. Their tensile strength and fracture strain increase compared to cast state up to 600 MPa and 4% correspondingly. Full article

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