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Electronic structure, electron-phonon coupling, and superconductivity in noncentrosymmetric ThCoC2 from ab initio calculations

引用

Physical Review B 2021年第9期104卷 094502-094502页

作者： Gabriel Kuderowicz Paweł Wójcik Bartlomiej Wiendlocha Faculty of Physics and Applied Computer Science AGH University of Science and Technology Aleja Mickiewicza 30 Krakow 30-059 Poland

Superconductors without inversion symmetry in their crystal structure are known to exhibit unconventional properties. Recently, based on the measured temperature dependence of the magnetic field penetration depth, superconductivity in noncentrosymmetric ThCoC2 was proposed to be a nodal d wave and mediated by the spin fluctuations. Moreover, a non-BCS behavior of the temperature dependence of the electronic specific heat and the magnetic upper critical field were reported. In this work, the electronic structure, phonons, and electron-phonon coupling are studied in ThCoC2 on the basis of ab initio computations. The effect of the spin-orbit coupling on the electronic structure and electron-phonon interaction is analyzed, and a large splitting of the electronic band structure is found. The calculated electron-phonon coupling constant λ=0.59 remains in decent agreement with the experimental estimates, suggesting that the electron-phonon interaction is strong enough to explain superconductivity with Tc≃2.5 K. Nevertheless, we show that the conventional isotropic Eliashberg formalism is unable to describe the thermodynamic properties of the superconducting state, as calculated temperature dependence of the electronic specific heat and magnetic penetration depth deviate from experiments, which is likely driven by the strong spin-orbit coupling and inversion symmetry breaking. In addition, to shed more light on the pairing mechanism, we propose to measure the carbon isotope effect, as our calculations based on the electron-phonon coupling predict the observation of the isotope effect with an exponent α≃0.15.

关键词： Electron-phonon coupling Spin-orbit coupling Superconductivity Noncentrosymmetric materials Density functional calculations

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Kink movement on a periodic background

arXiv

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arXiv 2024年

作者： Dobrowolski, Tomasz Gatlik, Jacek Kevrekidis, Panayotis G. Department of Computer Physics and Quantum Computing University of the National Education Commission in Krakow Podchoŗ azych 2 Cracow30-084 Poland AGH University of Krakow Faculty of Physics and Applied Computer Science Krakow30-059 Poland Department of Mathematics and Statistics University of Massachusetts AmherstMA01003-4515 United States

The behavior of the kink in the sine-Gordon (sG) model in the presence of periodic inhomogeneity is studied. An ansatz is proposed that allows for the construction of a reliable effective model with two degrees of freedom. Effective models featuring very good agreement with the original field-theoretic partial differential equation are constructed, including in the non-perturbative region and for relativistic velocities. The numerical solutions of the sG model describing the evolution of the kink in the presence of a barrier as well as in the case of a periodic heterogeneity under the potential additional influence of a switched bias current and/or dissipation were obtained. The results of the field equation and the effective models were favorably compared. The effect of the choice of initial conditions in the field model on the agreement of the results with the effective model is also discussed. © 2024, CC BY.

关键词： sine-Gordon equation

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Holes in Convex and Simple Drawings 32

Holes in Convex and Simple Drawings

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32nd International Symposium on Graph Drawing and Network Visualization, GD 2024

作者： Bergold, Helena Orthaber, Joachim Scheucher, Manfred Schröder, Felix Institute of Computer Science Freie Universität Berlin Germany TUM School of Computation Information and Technology Technische Universität München Germany Institute of Software Technology Graz University of Technology Austria Institut Für Mathematik Technische Universität Berlin Germany Department of Applied Mathematics Faculty of Mathematics and Physics Charles University Prague Czech Republic Institute of Mathematics Technische Universität Berlin Germany

ISBN: (纸本)9783959773430

Gons and holes in point sets have been extensively studied in the literature. For simple drawings of the complete graph a generalization of the Erdos-Szekeres theorem is known and empty triangles have been investigated. We introduce a notion of k-holes for simple drawings and study their existence with respect to the convexity hierarchy. We present a family of simple drawings without 4-holes and prove a generalization of Gerken's empty hexagon theorem for convex drawings. A crucial intermediate step will be the structural investigation of pseudolinear subdrawings in convex drawings. © Helena Bergold, Joachim Orthaber, Manfred Scheucher, and Felix Schröder.

关键词： Geometry

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Scaled tight binding model for a two dimensional electron gas at the (001) LaAlO3/SrTiO3 interface

arXiv

引用

arXiv 2024年

作者： Wójcik, Pawel Citro, Roberta Szafran, Bartlomiej AGH University of Krakow Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland Physics Department E. R. Caianiello' and CNR-SPIN Università degli Studi di Salerno SA Fisciano Italy

The progress in the fabrication of nanoscale systems based on the two-dimensional electron gas at the interface between LaAlO3 and SrTiO3 (LAO/STO) has created an increased demand for simulations of these nanostructures, which typically range in size from tens to hundreds of nanometers. Due to the low lattice constant of LAO/STO, approximately 0.394 nm, these calculations become extremely time-consuming. Here, we present a scaled tight-binding approximation defined on a mesh with size that can be several times larger than in the ordinary approach. The scaled model is analyzed within the context of quantum transport simulations and electronic structure calculations. Our findings demonstrate that the scaled model closely aligns with the ordinary one up to a scaling factor of 8. These results pave the way for more efficient simulations of LAO/STO nanostructures with realistic sizes relevant to experimental applications. © 2024, CC BY.

关键词： Electron gas

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Pseudo-observables and Deep Neural Network for mixed CP H → ττ decays at LHC

arXiv

引用

arXiv 2024年

作者： Richter-Was, E. Yerniyazov, T. Was, Z. Institute of Physics Jagiellonian University Lojasiewicza 11 Kraków30-348 Poland Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Lojasiewicza 11 Kraków30-348 Poland Institute of Nuclear Physics IFJ-PAN Radzikowskiego 152 Kraków31-342 Poland

The consecutive steps of cascade decay initiated by H → ττ can be useful for the measurement of Higgs couplings and in particular of the Higgs boson parity. The standard analysis method applied so far by ATLAS and CMS Collaborations was to fit a one-dimensional distribution of the angle between reconstructed decay planes of the τ lepton decays, ∗, which is sensitive to transverse spin correlations of the τ decays and, hence, to the CP state mixing angle, CP. Machine Learning techniques (ML) offer opportunities to manage such complex multidimensional signatures. The multidimensional signatures, the 4-momenta of the τ decay products can be used directly as input information to the machine learning algorithms to predict the CP-sensitive pseudo-observables and/or provide discrimination between different CP hypotheses. In the previous papers, we have shown that multidimensional signatures, the 4-momenta of the τ decay products can be used as input information to the machine learning algorithms to predict the CP-sensitive pseudo-observables and/or provide discrimination between different CP hypotheses. In this paper we show how the classification or regression methods can be used to train an ML model to predict the spin weight sensitive to the CP state of the decaying Higgs boson, parameters of the functional form of the spin weight, or the most preferred CP mixing angle of the analysed sample. The one-dimensional distribution of the predicted spin weight or the most preferred CP mixing angle of the experimental data can be examined further, with the statistical methods, to derive the measurement of the CP mixing state of the Higgs signal events in decay H → ττ. This paper extends studies presented in our previous publication, with more experimentally realistic scenarios for the features lists and further development of strategies how proposed pseudo-observables can be used in the measurement. Copyright © 2024, The Authors. All rights reserved.

关键词： Bosons

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Secrecy Outage Probability of Full-Duplex Relaying Vehicular Networks 10

Secrecy Outage Probability of Full-Duplex Relaying Vehicular...

引用

10th International Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2022

作者： Abd El Ghafour, Mohamed G. Abd El-Malek, Ahmed H. Hassan, Ola E. Abo-Zahhad, Mohammed Alexandria University Faculty of Engineering Department of Engineering Mathematics and Physics Alexandria21544 Egypt Egypt-Japan University of Science & Technology School of Electronics Communications & Computer Engineering Alexandria21934 Egypt Arab Academy for Science Technology & Maritime Transport Basic and Applied Science Department Smart Village Campus Giza12577 Egypt Assiut University Faculty of Engineering Electrical Engineering Department Assiut71515 Egypt

ISBN: (纸本)9781665464635

This paper investigates the secrecy performance of full-duplex cooperative vehicular relaying networks under passive eavesdropping attacks in the presence of co-channel interference. In the considered system model, a static source communicates with a static destination through a mobile full-duplex relay in the presence of a mobile passive eavesdropper and a static co-channel interferer. A closed-form expression for the exact secrecy outage probability of the system is derived for the Nakagami-m fading environment. Hence, the asymptotic secrecy outage probability is obtained at high signal-to-noise values. Numerical and Simulation results are obtained to validate the derived analytical expressions. © 2022 IEEE.

关键词： Signal to noise ratio

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Constraining the Bispectrum from Bouncing Cosmologies with Planck

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Physical Review Letters 2023年第19期130卷 191002-191002页

作者： Bartjan van Tent Paola C. M. Delgado Ruth Durrer Université Paris-Saclay CNRS/IN2P3 IJCLab 91405 Orsay France Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University 30-348 Krakow Poland Department of Theoretical Physics Université de Genève Quai Ernest Ansermet 24 Genève 1211 Switzerland

Bouncing models of cosmology, as they arise, e.g., in loop quantum cosmology, can be followed by an inflationary phase and generate close-to-scale-invariant fluctuation spectra as observed in the cosmic microwave background (CMB). However, they are typically not Gaussian and also generate a bispectrum. These models can help to mitigate the large-scale anomalies of the CMB by considering substantial non-Gaussianities on very large scales, which decay exponentially on subhorizon scales. It was therefore thought that this non-Gaussianity would not be visible in observations, which can only probe subhorizon scales. We show that bouncing models with parameters such that they can significantly mitigate the large-scale anomalies of the CMB are excluded by the Planck data with high significance of, depending on the specific model, 5.4, 6.4, or 14 standard deviations.

关键词： Cosmic microwave background Quantum cosmology Quantum gravity

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Effect of Magnetism on Lattice Vibrations: Mössbauer Spectroscopic Evidence

arXiv

引用

arXiv 2022年

作者： Dubiel, Stanislaw M. Faculty of Physics and Applied Computer Science Academic Center for Materials and Nanotechnology AGH University of Science and Technology KrakówPL-30-059 Poland

Based on the available literature reviewed are results pertinent to the effect of magnetism on lattice dynamics obtained by Mössbauer spectroscopy at 57Fe and 119Sn probe atoms. Presented and discussed are sigma-phase Fe-Cr, Fe-V, Fe-Cr-Ni and λ-phase (C14 Laves) NbFe2 compounds that belong to the Frank-Kasper family of phases, metallic chromium and iron mono-arsenide, FeAs. The common feature of all these metallic systems is itinerant character of their magnetism. Two spectral parameters relevant to the lattice dynamics viz. the center shift, CS, and/or the recoil-free fraction, f, are considered as figures of merit. Their temperature dependences show anomalies at magnetic ordering temperatures giving evidence that that vibrations in the magnetic phase are different than those in the paramagnetic phase. The lower the magnetic ordering temperature, the stronger the difference. Copyright © 2022, The Authors. All rights reserved.

关键词： Ternary alloys

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SELECTED ASPECTS OF PLANETARY physics

Acta Physica Polonica B, Proceedings Supplement

引用

Acta Physica Polonica B, Proceedings Supplement 2025年第3期18卷

作者： Kozakiewicz, J. Gurgurewicz, J. Mège, D. Olszewski, R. Blęcka, M.I. Choromański, K. Czechowski, L. Czernic, P. Frodyma, N. Orlanducci, C. Poppe, S. Tesson, P.-A. Zalewska, N. Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Lojasiewicza 11 Kraków30-348 Poland Centrum Badań Kosmicznych Polskiej Akademii Nauk Bartycka 18A Warsaw00-716 Poland Faculty of Geodesy and Cartography Warsaw University of Technology pl. Politechniki 1 Warsaw00-661 Poland

We give an overview of Polish activities in planetary physics, based on contributions presented at the National Mars science Seminars and the Planetary science Conference held at the Jagiellonian University in Kraków since 2019. During the five editions of the conference, about 50 presentations were discussed showing how robust and important the role of the Polish scientific community in planetary science is. © 2025 Jagiellonian University. All rights reserved.

关键词： Astrophysics

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Electronic and Topological Properties of a Topological Insulator Thin Film Sandwiched between Ferromagnetic Insulators

arXiv

引用

arXiv 2023年

作者： Pigon, Piotr Dyrdal, Anna AGH University of Krakow Faculty of Physics and Applied Computer Science al. Adama Mickiewicza 30 Kraków30-059 Poland Department of Mesoscopic Physics ISQI Faculty of Physics Adam Mickiewicz University ul. Uniwersytetu Poznańskiego 2 Poznań61-614 Poland

We consider a thin film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the anomalous quantum Hall state. © 2023, CC BY.

关键词： Magnetization

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