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.
- Journal Rank: CiteScore - Q2 (Condensed Matter Physics)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 20.3 days after submission; acceptance to publication is undertaken in 3.9 days (median values for papers published in this journal in the second half of 2023).
- 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:
1.7 (2022);
5-Year Impact Factor:
1.6 (2022)
Latest Articles
FL Approach to the Coexistence of Fermi Arcs with Metal–Insulator Crossover in Strongly Underdoped Cuprates*
Condens. Matter 2024, 9(1), 9; https://doi.org/10.3390/condmat9010009 - 15 Jan 2024
Abstract
We propose that one can explain the coexistence in the same range of doping and temperature of gapless Fermi arcs with the metal–insulator crossover of in-plane resistivity in strongly underdoped cuprates in terms of the FL* fractionalized Fermi liquid nature of these systems,
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We propose that one can explain the coexistence in the same range of doping and temperature of gapless Fermi arcs with the metal–insulator crossover of in-plane resistivity in strongly underdoped cuprates in terms of the FL* fractionalized Fermi liquid nature of these systems, and that such coexistence is not due simply to disorder effects in the resistivity. The particle excitations of this FL* system derived from variants of the t-J model are the gapless holon carrying charge with small Fermi momentum proportional to the doping, the gapful spinon carrying spin 1/2, and an emergent gauge field coupling them and the hole as a spinon–holon bound state, or more precisely resonance, due to gauge binding, with a Fermi surface respecting the topological Luttinger theorem. In our proposal, Fermi arcs are determined by the hole resonance, whereas the metal–insulator crossover is dominated by spinon–spinon (with subleading holon–holon) gauge interactions, and this dichotomy is able to explain their coexistence.
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(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))
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Fully Microscopic Treatment of Magnetic Field Using Bogoliubov–De Gennes Approach
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Condens. Matter 2024, 9(1), 8; https://doi.org/10.3390/condmat9010008 - 15 Jan 2024
Abstract
This work introduces an algorithm designed to solve the Bogoliubov–de Gennes equations of superconductivity theory. What sets this algorithm apart is its remarkable ability to precisely and consistently consider the impact of an external magnetic field, all within the microscopic approach. The computation
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This work introduces an algorithm designed to solve the Bogoliubov–de Gennes equations of superconductivity theory. What sets this algorithm apart is its remarkable ability to precisely and consistently consider the impact of an external magnetic field, all within the microscopic approach. The computation scheme’s convergence is guaranteed by addressing the Biot–Savart equation for the field where the vector potential appears on both of its sides. To showcase the capabilities of this approach, we provide several key examples: the Abrikosov lattice, vortex core states, and the vortex structure in the intermediate mixed state of a superconductor. This method promises to offer valuable insights into the microscopic physics of intertype superconductivity.
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(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))
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Microwave Field-Induced Changes in Raman Modes and Magnetic Force Images of Antiferromagnetic NiO Films
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, , , , , and
Condens. Matter 2024, 9(1), 7; https://doi.org/10.3390/condmat9010007 - 15 Jan 2024
Abstract
Effective control of domain walls or magnetic textures in antiferromagnets promises to enable robust, fast, and nonvolatile memories. The lack of net magnetic moment in antiferromagnets implies the need for creative ways to achieve such a manipulation. We conducted a study to investigate
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Effective control of domain walls or magnetic textures in antiferromagnets promises to enable robust, fast, and nonvolatile memories. The lack of net magnetic moment in antiferromagnets implies the need for creative ways to achieve such a manipulation. We conducted a study to investigate changes in magnetic force microscopy (MFM) imaging and in the magnon-related mode in Raman spectroscopy of virgin NiO films under a microwave pump. After MFM and Raman studies were conducted, a combined action of broadband microwave (0.01–20 GHz, power scanned from to 5 dBm) and magnetic field (up to 3 kOe) were applied to virgin epitaxial (111) NiO and (100) NiO films grown on (0001) Al O and (100) MgO substrates, following which the MFM and Raman studies were repeated. We observed a suppression of the magnon-related Raman mode subsequent to the microwave exposure. Based on MFM imaging, this effect appeared to be caused by the suppression of large antiferromagnetic domain walls due to the possible excitation of antiferromagnetic spin oscillations localized within the antiferromagnetic domain walls.
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(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))
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The Impact of Short-Range (Gaussian) Disorder Correlations on Superconducting Characteristics
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Condens. Matter 2024, 9(1), 6; https://doi.org/10.3390/condmat9010006 - 12 Jan 2024
Abstract
The pursuit of enhanced superconducting device performance has historically focused on minimizing disorder in materials. Recent research, however, challenges this conventional wisdom by exploring the unique characteristics of disordered materials. Following the studies, disorder is currently viewed as a design parameter that can
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The pursuit of enhanced superconducting device performance has historically focused on minimizing disorder in materials. Recent research, however, challenges this conventional wisdom by exploring the unique characteristics of disordered materials. Following the studies, disorder is currently viewed as a design parameter that can be tuned. This shift in the paradigm has sparked an upsurge in research efforts, which demonstrates that disorder can significantly augment the superconductivity figures of merit. While almost all previous studies attended to the effects related to disorder strength, this article focuses on the impact of short-range disorder correlations that in real materials takes place, for example, due to lattice defects. The study shows that the degree of such correlations can strongly influence the superconducting characteristics.
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(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))
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Comparison of Different Methods for Evaluating Quantitative X-ray Fluorescence Data in Copper-Based Artefacts
Condens. Matter 2024, 9(1), 5; https://doi.org/10.3390/condmat9010005 - 11 Jan 2024
Abstract
Handheld X-ray Fluorescence devices (HH-XRF) have given archaeologists and conservators the opportunity to study a wide range of materials encountered in their work with great accessibility and flexibility. The investigation of copper-based artefacts is a frequent application of these instruments in the field
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Handheld X-ray Fluorescence devices (HH-XRF) have given archaeologists and conservators the opportunity to study a wide range of materials encountered in their work with great accessibility and flexibility. The investigation of copper-based artefacts is a frequent application of these instruments in the field of cultural heritage as it gives direct and rapid quantitative results that can provide very important information about them, such as their fabrication technology. This paper discusses the comparison of quantitative results, obtained by a commercial handheld XRF device “Bruker Tracer 5g” on certified standards, compositionally significant in copper-based alloys of interest in the field of cultural heritage. The measured elemental concentrations were derived using three different calibrations, which were examined for their accuracy. Two of them were based on the empirical coefficients approach, performed by the built-in calibration/software (copper alloy calibrations provided by Bruker manufacturer and the Bruker EasyCal software), while the third one was performed off-line by processing the spectra with an independent fundamental parameters (FP) software (PyMca version 5.9.2., a X-ray fluorescence analysis software developed at the European Synchrotron Radiation Facility). The results highlight that although HH-XRF devices simplify data collection, for optimal quantitative results, the correct choice of analysis conditions and calibration method still requires a detailed understanding of the principles of X-ray spectrometry.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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On the Importance of Future, Precise, X-ray Measurements in Kaonic Atoms
Condens. Matter 2024, 9(1), 4; https://doi.org/10.3390/condmat9010004 - 11 Jan 2024
Abstract
Progress in the construction of precise X-ray detectors allows measurements of energies and widths of “upper levels” in K− mesic atoms. These can be used to determine sub-threshold Kaon-nucleon amplitudes, which are important in investigations of nuclear states of these mesons. The
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Progress in the construction of precise X-ray detectors allows measurements of energies and widths of “upper levels” in K− mesic atoms. These can be used to determine sub-threshold Kaon-nucleon amplitudes, which are important in investigations of nuclear states of these mesons. The special case of the 2P state in Kaonic Helium is discussed and used to check the properties of the K− proton quasi-bound state. Similar attempts in other elements indicate a need for new, precise measurements.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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SrTiO3: Thoroughly Investigated but Still Good for Surprises
Condens. Matter 2024, 9(1), 3; https://doi.org/10.3390/condmat9010003 - 06 Jan 2024
Abstract
For decades, SrTiO3 has been in the focus of research with seemingly never-ending new insights regarding its ground state properties, application potentials, its surface and interface properties, the superconducting state, the twin boundaries, domain functionalities, etc. Here, we focus on the already
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For decades, SrTiO3 has been in the focus of research with seemingly never-ending new insights regarding its ground state properties, application potentials, its surface and interface properties, the superconducting state, the twin boundaries, domain functionalities, etc. Here, we focus on the already well-investigated lattice dynamics of STO and show that four different temperature regimes can be identified which dominate the elastic properties, the thermal conductivity, and the birefringence. These regimes are a low-temperature quantum fluctuation-dominated one, followed by an intermediate regime, a region of structural phase transition at ~105 K and its vicinity, and at high temperatures, a regime characterized by precursor and saturation effects. They can all be elucidated by lattice dynamical aspects. The relevant temperature dependences of the soft modes are discussed and their relationship to lattice polarizability is emphasized.
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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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Influence of Energetic Particles and Electron Injection on Minority Carrier Transport Properties in Gallium Oxide
Condens. Matter 2024, 9(1), 2; https://doi.org/10.3390/condmat9010002 - 06 Jan 2024
Abstract
The influence of various energetic particles and electron injection on the transport of minority carriers and non-equilibrium carrier recombination in Ga2O3 is summarized in this review. In Ga2O3 semiconductors, if robust p-type material and bipolar structures become
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The influence of various energetic particles and electron injection on the transport of minority carriers and non-equilibrium carrier recombination in Ga2O3 is summarized in this review. In Ga2O3 semiconductors, if robust p-type material and bipolar structures become available, the diffusion lengths of minority carriers will be of critical significance. The diffusion length of minority carriers dictates the functionality of electronic devices such as diodes, transistors, and detectors. One of the problems in ultrawide-bandgap materials technology is the short carrier diffusion length caused by the scattering on extended defects. Electron injection in n- and p-type gallium oxide results in a significant increase in the diffusion length, even after its deterioration, due to exposure to alpha and proton irradiation. Furthermore, post electron injection, the diffusion length of an irradiated material exceeds that of Ga2O3 prior to irradiation and injection. The root cause of the electron injection-induced effect is attributed to the increase in the minority carrier lifetime in the material due to the trapping of non-equilibrium electrons on native point defects. It is therefore concluded that electron injection is capable of “healing” the adverse impact of radiation in Ga2O3 and can be used for the control of minority carrier transport and, therefore, device performance.
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(This article belongs to the Special Issue Wide-Band-Gap Semiconductors for Energy and Electronics)
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Design and Use of Portable X-ray Fluorescence Devices for the Analysis of Heritage Materials
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, , , , , and
Condens. Matter 2024, 9(1), 1; https://doi.org/10.3390/condmat9010001 - 06 Jan 2024
Abstract
X-ray fluorescence (XRF) is a successful technique often used for the elemental analysis of cultural heritage artefacts. It is non-invasive, the equipment can be miniaturized and made portable and it allows addressing crucial issues such as the fabrication technology, authenticity and provenance of
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X-ray fluorescence (XRF) is a successful technique often used for the elemental analysis of cultural heritage artefacts. It is non-invasive, the equipment can be miniaturized and made portable and it allows addressing crucial issues such as the fabrication technology, authenticity and provenance of the artefacts. Depending on the components’ selection (e.g., the primary source, the detector and the focusing optics, if present), the analytical performance and the consequent suitability to investigate a given class of materials may vary significantly. The present paper discusses the analytical performance—with special regard to the limits of detection and the quantification uncertainty—of two portable XRF spectrometers developed within a collaboration between INFN-LNF-FISMEL and CNR-ISPC. The devices are expressly designed for heritage materials. In particular, one is equipped with focusing optics and it is intended to analyze small details on glasses and pigmented surfaces, whereas the other has a 70 kV X-ray tube, which greatly improves sensitivity for medium-Z elements, which is important in copper-based artefacts. Finally, this paper discusses two case studies to highlight the features of the instruments: one concerns Etruscan vitreous material beads and the other pre- and proto-historic copper-based artefacts from Tyrrhenian Central Italy. Thanks to the small size of the equipment, both investigations could easily be carried out in situ, namely, at the Museo Nazionale Etrusco in Rome and the Museo della Preistoria della Tuscia e della Rocca Farnese at Valentano.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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The Cryogenic Anticoincidence Detector for the NewAthena X-IFU Instrument: A Program Overview
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Condens. Matter 2023, 8(4), 108; https://doi.org/10.3390/condmat8040108 - 13 Dec 2023
Abstract
Athena (advanced telescope for high-energy astrophysics) is an ESA large-class mission, at present under a re-definition “design-to-cost” phase, planned for a prospective launch at L1 orbit in the second half of the 2030s. It will be an observatory alternatively focusing on two complementary
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Athena (advanced telescope for high-energy astrophysics) is an ESA large-class mission, at present under a re-definition “design-to-cost” phase, planned for a prospective launch at L1 orbit in the second half of the 2030s. It will be an observatory alternatively focusing on two complementary instruments: the X-IFU (X-ray Integral Field Unit), a TES (TransitionEdge Sensor)-based kilo-pixel array which is able to perform simultaneous high-grade energy spectroscopy (~3 eV@7 keV) and imaging over 4′ FoV (field of view), and the WFI (Wide Field Imager), which has good energy spectral resolution (~170 eV@7 keV) and imaging on wide 40′ × 40′ FoV. Athena will be a truly transformational observatory, operating in conjunction with other large observatories across the electromagnetic spectrum available in the 2030s like ALMA, ELT, JWST, SKA, CTA, etc., and in multi-messenger synergies with facilities like LIGO A+, Advanced Virgo+, LISA, IceCube and KM3NeT. The Italian team is involved in both instruments. It has the co-PIship of the cryogenic instrument for which it has to deliver the TES-based Cryogenic AntiCoincidence detector (CryoAC) necessary to guarantee the X-IFU sensitivity, degraded by a primary particle background of both solar and galactic cosmic ray (GCR) origins, and by secondary electrons produced by primaries interacting with the materials surrounding the main detector. The outcome of Geant4 studies shows the necessity for adopting both active and passive techniques to guarantee the residual particle background at 5 × 10−3 cts cm−2 s−1 keV−1 level in 2–10 keV scientific bandwidth. The CryoAC is a four-pixel detector made of Si-suspended absorbers sensed by Ir/Au TESes placed at <1 mm below the main detector. After a brief overview of the Athena mission, we will report on the particle background reduction techniques highlighting the impact of the Geant4 simulation on the X-IFU focal plane assembly design, then hold a broader discussion on the CryoAC program in terms of detection chain system requirements, test, design concept against trade-off studies and programmatic.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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Single-Band versus Two-Band Description of Magnetism in Infinite-Layer Nickelates
Condens. Matter 2023, 8(4), 107; https://doi.org/10.3390/condmat8040107 - 06 Dec 2023
Abstract
We present a weak-coupling analysis of magnetism in infinite-layer nickelates, where we compare a single-band description with a two-band model. Both models predict that (i) hybridization due to hopping is negligible, and ( ) the magnetic properties are characterized
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We present a weak-coupling analysis of magnetism in infinite-layer nickelates, where we compare a single-band description with a two-band model. Both models predict that (i) hybridization due to hopping is negligible, and ( ) the magnetic properties are characterized by very similar dynamic structure factors, , at the points and . This gives effectively a two-dimensional description of the magnetic properties.
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(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)
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Impact of Solid-State Charge Injection on Spectral Photoresponse of NiO/Ga2O3 p–n Heterojunction
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Condens. Matter 2023, 8(4), 106; https://doi.org/10.3390/condmat8040106 - 02 Dec 2023
Abstract
Forward bias hole injection from 10-nm-thick p-type nickel oxide layers into 10-μm-thick n-type gallium oxide in a vertical NiO/Ga2O3 p–n heterojunction leads to enhancement of photoresponse of more than a factor of 2 when measured from this junction. While it
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Forward bias hole injection from 10-nm-thick p-type nickel oxide layers into 10-μm-thick n-type gallium oxide in a vertical NiO/Ga2O3 p–n heterojunction leads to enhancement of photoresponse of more than a factor of 2 when measured from this junction. While it takes only 600 s to obtain such a pronounced increase in photoresponse, it persists for hours, indicating the feasibility of photovoltaic device performance control. The effect is ascribed to a charge injection-induced increase in minority carrier (hole) diffusion length (resulting in improved collection of photogenerated non-equilibrium carriers) in n-type β-Ga2O3 epitaxial layers due to trapping of injected charge (holes) on deep meta-stable levels in the material and the subsequent blocking of non-equilibrium carrier recombination through these levels. Suppressed recombination leads to increased non-equilibrium carrier lifetime, in turn determining a longer diffusion length and being the root-cause of the effect of charge injection.
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(This article belongs to the Special Issue Wide-Band-Gap Semiconductors for Energy and Electronics)
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Advances in P(VDF-TrFE) Composites: A Methodical Review on Enhanced Properties and Emerging Electronics Applications
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Condens. Matter 2023, 8(4), 105; https://doi.org/10.3390/condmat8040105 - 01 Dec 2023
Abstract
Piezoelectric polymers are a class of material that belong to carbon–hydrogen-based organic materials with a long polymer chain. They fill the void where single crystals and ceramics fail to perform. This characteristic of piezoelectric polymers made them unique. Their piezoelectric stress constant is
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Piezoelectric polymers are a class of material that belong to carbon–hydrogen-based organic materials with a long polymer chain. They fill the void where single crystals and ceramics fail to perform. This characteristic of piezoelectric polymers made them unique. Their piezoelectric stress constant is higher than ceramics and the piezoelectric strain is lower compared to ceramics. This study’s goal is to present the most recent information on poly(vinylidene fluoride) with trifluoroethylene P(VDF-TrFE), a major copolymer of poly(vinylidene fluoride) PVDF with piezoelectric, pyroelectric, and ferroelectric characteristics. The fabrication of P(VDF-TrFE) composites and their usage in a variety of applications, including in actuators, transducers, generators, and energy harvesting, are the primary topics of this work. The report provides an analysis of how the addition of fillers improves some of the features of P(VDF-TrFE). Commonly utilized polymer composite preparation techniques, including spinning, Langmuir–Blodgett (LB), solution casting, melt extrusion, and electrospinning are described, along with their effects on the pertinent characteristics of the polymer composite. A brief discussion on the literature related to different applications (such as bio-electronic devices, sensors and high energy-density piezoelectric generators, low mechanical damping, and easy voltage rectifiers of the polymer composite is also presented.
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(This article belongs to the Special Issue New Advances in Condensed Matter Physics)
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Hybrid Superconducting/Superconducting Mesoscopic Heterostructure Studied by Modified Ginzburg–Landau Equations
Condens. Matter 2023, 8(4), 104; https://doi.org/10.3390/condmat8040104 - 01 Dec 2023
Abstract
Studies involving vortexes in hybrid superconducting devices and their interactions with different components inside samples are important for reaching higher values of critical parameters in superconducting materials. The vortex distribution on each side of a sample with different fundamental parameters, such as temperature
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Studies involving vortexes in hybrid superconducting devices and their interactions with different components inside samples are important for reaching higher values of critical parameters in superconducting materials. The vortex distribution on each side of a sample with different fundamental parameters, such as temperature T, penetration depth , coherence length , electron mass m, and the order parameter , may help to improve the superconducting properties. Thus, in this work, we used the modified Ginzburg–Landau theory to investigate a hybrid superconductor (HS), as well as to provide a highly tunable and adjustable theoretical tool for theoretically explaining the experimental results involving the HS in order to study the vortex behavior in superconductors of mesoscopic dimensions with extreme differences among their fundamental parameters. Therefore, we evaluated the influence of the HS on the vortex configuration and its effects on field-dependent magnetization. The results show that when the applied magnetic field H was increased, the diamagnetic response of the HS (Meissner effect) included additional jumps in magnetization, while diamagnetism continued to increase in the sample. In addition, the differences among parameters created an interface between both components, and two different magnitudes of supercurrent and vortex sizes caused less degradation of the local superconductivity, which increased the upper critical field. On the other hand, this type of HS with differences in parameters on both sides can be used to control the vortex movement in the selected sample of the superconducting region with more accuracy.
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(This article belongs to the Special Issue Multicomponent Superconductivity and Superfluidity)
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Fluorescence and Raman Micro-Spectroscopy of LiF Films Containing Radiation-Induced Defects for X-ray Detection
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Condens. Matter 2023, 8(4), 103; https://doi.org/10.3390/condmat8040103 - 30 Nov 2023
Abstract
Lithium fluoride (LiF) film detectors for extreme ultraviolet radiation, soft and hard X-rays, based on the photoluminescence of radiation-induced electronic defects, have been proposed and are currently under further development and investigation. LiF film detectors are versatile and can be integrated in different
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Lithium fluoride (LiF) film detectors for extreme ultraviolet radiation, soft and hard X-rays, based on the photoluminescence of radiation-induced electronic defects, have been proposed and are currently under further development and investigation. LiF film detectors are versatile and can be integrated in different experimental apparatus and imaging configurations. LiF can be grown in the form of polycrystalline thin films and it is compatible with several substrates. The radiation-induced color center (CCs) photoluminescence (PL) response can be enhanced through the appropriate choice of substrates and multilayer designs, and by tailoring the micro-structural properties of polycrystalline LiF films through the control of the growth conditions. In this work, we present the characterization, through fluorescence and Raman micro-spectroscopy, of LiF films, thermally evaporated on different substrates with thicknesses of up to 1 μm, irradiated with soft X-rays produced by a laser plasma source. The combination of these micro-spectroscopy techniques could represent an advanced method to investigate the role of the polycrystalline film structures in CC formation efficiency at the microscopic level, a fundamental aspect of the development of LiF film radiation-imaging detectors.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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Effect of Growth and Calcination Temperatures on the Optical Properties of Ruthenium-Doped ZnO Nanoparticles
Condens. Matter 2023, 8(4), 102; https://doi.org/10.3390/condmat8040102 - 29 Nov 2023
Abstract
This study aimed to probe the effect of heat treatment on zinc oxide nanoparticles doped with ruthenium through a chemical co-preparation technique. Pure ZnO and Ru-doped ZnO nanoparticles, with the general formula Zn1−x−RuxO, were synthesized for 0 ≤ x
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This study aimed to probe the effect of heat treatment on zinc oxide nanoparticles doped with ruthenium through a chemical co-preparation technique. Pure ZnO and Ru-doped ZnO nanoparticles, with the general formula Zn1−x−RuxO, were synthesized for 0 ≤ x ≤ 0.04. Using the same starting precursors, the growth temperature was 60 °C and 80 °C for set A and set B, respectively, whereas the calcination temperature was 450 °C and 550 °C for set A and set B, respectively. For the structure investigation, X-ray powder diffraction (XRD) revealed that the crystallite size of set A was smaller than that of set B. For x = 0.04 in set B, the maximum value of the crystallite size was attributed to the integration of Ru3+ ions into interstitial sites in the host causing this expansion. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of zinc oxide nanoparticles by showing a Zn-O bonding peak at 421 cm−1. For x = 0.04 in set B, the divergence confirmed the change in bonding properties of Zn2+ distributed by Ru3+ doping, which verifies the presence of secondary-phase RuO2. Using UV–visible spectroscopy, the energy gap of set A swings as ruthenium doping increases. However, in set B, as the crystallite size decreases, the energy gap increases until reversing at the highest concentration of x = 0.04. The transition from oxygen vacancy to interstitial oxygen, which is associated with the blue peak (469 nm), increases in set A under low heating conditions and decreases in set B as Ru doping increases, as revealed in the photoluminescence optical spectra of the samples. Therefore, ruthenium doping proves a useful surface defect and generates distortion centers in the lattice, leading to more adsorption and a remarkable advantage in sunscreen and paint products used for UV protection.
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(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Superconductivity and Magnetism (ICSM2023))
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The Implementation of MuDirac in Geant4: A Preliminary Approach to the Improvement of the Simulation of the Muonic Atom Cascade Process
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Condens. Matter 2023, 8(4), 101; https://doi.org/10.3390/condmat8040101 - 17 Nov 2023
Abstract
Muonic Atom X-ray Emission spectroscopy (µ-XES) is a novel elemental technique that exploits the high-energy X-rays emitted from the muonic atom cascade process to characterize materials. At the ISIS Neutron and Muon Source, the technique is performed at Port4 of the RIKEN-RAL facility,
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Muonic Atom X-ray Emission spectroscopy (µ-XES) is a novel elemental technique that exploits the high-energy X-rays emitted from the muonic atom cascade process to characterize materials. At the ISIS Neutron and Muon Source, the technique is performed at Port4 of the RIKEN-RAL facility, with a user demand that is increasing every year. To cope with this demand, it is necessary to continue to improve the method, either for the hardware (detectors, acquisition, etc.) or software (data analysis and interpretation). In both cases, Monte Carlo codes play an important role: with a simulation, it is possible to reproduce the experimental setup and provide a reliable quantitative analysis. In this work, we investigate the capabilities of GEANT4 for such applications. From the results, we observed that the generation of X-rays, especially the kα and kβ transition for high Z atoms, are not in agreement with the experimental ones. A solution to this issue, other than an attempt with a small modification of the GEANT4 cascade class, could be provided by a database of transition energy calculated by a Dirac equation software called MuDirac. The software, developed by the UKRI scientific computing department and the ISIS muon group, can compute all the transition energy for a given nuclide. Here, preliminary results of the implementation of the MuDirac database in GEANT4 are reported.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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Two-Dimensional Discommensurations: An Extension to McMillan’s Ginzburg–Landau Theory
Condens. Matter 2023, 8(4), 100; https://doi.org/10.3390/condmat8040100 - 17 Nov 2023
Abstract
Charge density waves (CDWs) profoundly affect the electronic properties of materials and have an intricate interplay with other collective states, like superconductivity and magnetism. The well-known macroscopic Ginzburg–Landau theory stands out as a theoretical method for describing CDW phenomenology without requiring a microscopic
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Charge density waves (CDWs) profoundly affect the electronic properties of materials and have an intricate interplay with other collective states, like superconductivity and magnetism. The well-known macroscopic Ginzburg–Landau theory stands out as a theoretical method for describing CDW phenomenology without requiring a microscopic description. In particular, it has been instrumental in understanding the emergence of domain structures in several CDW compounds, as well as the influence of critical fluctuations and the evolution towards or across lock-in transitions. In this context, McMillan’s foundational work introduced discommensurations as the objects mediating the transition from commensurate to incommensurate CDWs, through an intermediate nearly commensurate phase characterised by an ordered array of phase slips. Here, we extended the simplified, effectively one-dimensional, setting of the original model to a fully two-dimensional analysis. We found exact and numerical solutions for several types of discommensuration patterns and provide a framework for consistently describing multi-component CDWs embedded in quasi-two-dimensional atomic lattices.
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(This article belongs to the Special Issue Superstripes Physics, 2nd Edition)
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Improving the Time Resolution of Large-Area LaBr3:Ce Detectors with SiPM Array Readout
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Condens. Matter 2023, 8(4), 99; https://doi.org/10.3390/condmat8040099 - 17 Nov 2023
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Abstract
LaBr :Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1
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LaBr :Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1 round LaBr :Ce crystals to realize compact detectors with the SiPM array readout. The aim was a good energy resolution and a fast time response to detect low-energy X-rays around 100 keV. A natural application was found inside the FAMU experiment, at RIKEN RAL. Its aim is a precise measurement of the proton Zemach radius with impinging muons, to contribute to the solution to the so-called “proton radius puzzle”. Signals to be detected are characteristic X-rays around 130 KeV. A limit for this type of detector, as compared to the ones with a photomultiplier readout, is its poorer timing characteristics due to the large capacity of the SiPM arrays used. In particular, long signal falltimes are a problem in experiments such as FAMU, where a “prompt” background component must be separated from a “delayed” one (after 600 ns) in the signal X-rays to be detected. Dedicated studies were pursued to improve the timing characteristics of the used detectors, starting from hybrid ganging of SiPM cells; then developing a suitable zero pole circuit with a parallel ganging, where an increased overvoltage for the SiPM array was used to compensate for the signal decrease; and finally designing ad hoc electronics to split the 1 detector’s SiPM array into four quadrants, thus reducing the involved capacitances. The aim was to improve the detectors’ timing characteristics, especially falltime, while keeping a good FWHM energy resolution for low-energy X-ray detection.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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Combined Spectroscopy System Utilizing Gas Electron Multiplier and Timepix3 Technology for Laser Plasma Experiments
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, , , , , , and
Condens. Matter 2023, 8(4), 98; https://doi.org/10.3390/condmat8040098 - 17 Nov 2023
Abstract
We present an innovative X-ray spectroscopy system to address the complex study of the X-ray emissions arising from laser–target interactions, where the emissions occur within extremely brief intervals from femtoseconds to nanoseconds. Our system combines a Gas Electron Multiplier (GEM) detector with a
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We present an innovative X-ray spectroscopy system to address the complex study of the X-ray emissions arising from laser–target interactions, where the emissions occur within extremely brief intervals from femtoseconds to nanoseconds. Our system combines a Gas Electron Multiplier (GEM) detector with a silicon-based Timepix3 (TPX3) detector. These detectors work in tandem, allowing for a spectroscopic radiation analysis along the same line of sight. With an active area of 10 × 10 cm , the GEM detector allows for 1D measurements for X-ray energies (2–50 keV) by utilizing the full 10 cm gas depth. The high-energy part of the radiation beam exits through a downstream side window of the GEM without being absorbed in the gas volume. Positioned side-on at the GEM detector’s exit, the TPX3 detector, equipped with a pixelated sensor (55 µm × 55 µm; active area 14 mm × 14 mm), uses its full 14 mm silicon sensor to detect hard X-rays (50–500 keV) and gamma rays (0.5–10 MeV). We demonstrate the correct operation of the entire detection system and provide a detailed description of the Timepix3 detector’s calibration procedure, highlighting the suitability of the combined system to work in laser plasma facilities.
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(This article belongs to the Special Issue High Precision X-ray Measurements 2023)
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