Physica C-superconductivity and Its Applications最新文献

{"title":"Unusual electronic structure in underdoped cuprate superconductors","authors":"Xiang Li ,&nbsp;Minghuan Zeng ,&nbsp;Huaiming Guo ,&nbsp;Shiping Feng","doi":"10.1016/j.physc.2025.1354767","DOIUrl":"10.1016/j.physc.2025.1354767","url":null,"abstract":"<div><div>The underdoped cuprate superconductors are characterized by the opening of the normal-state pseudogap, while such an aspect of the normal-state pseudogap effect should be reflected in the low-energy electronic structure. Here the effect of the normal-state pseudogap on the low-energy electronic structure in the underdoped cuprate superconductors is investigated within the framework of the kinetic-energy-driven superconductivity. The strong coupling of the electrons with the spin excitation induces the normal-state pseudogap-state in the particle-hole channel and superconducting (SC) state in the particle–particle channel, where the normal-state pseudogap and SC gap respectively originate from the electron normal and anomalous self-energies, and are evaluated by taking into account the vertex correction. As a natural consequence of the interplay between the normal-state pseudogap-state and SC-state, the SC transition temperature <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> exhibits a dome-like shape of the doping dependence, however, in a striking contrast to <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> in the underdoped regime, the normal-state pseudogap crossover temperature <span><math><msup><mrow><mi>T</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span> is much higher than <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> in the underdoped regime, and then it decreases with the increase of doping, eventually disappearing together with <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> at the end of the SC dome. Concomitantly, the spectral weight on the electron Fermi surface (EFS) at around the antinodal region is suppressed strongly by this normal-state pseudogap, and then EFS is truncated to form four disconnected Fermi arcs centered around the nodal region with the largest spectral weight located at around the tips of the disconnected Fermi arcs. Moreover, the dip in the peak-dip-hump structure observed in the energy distribution curve and checkerboard charge ordering found in the ARPES autocorrelation are intrinsically connected with the emergence of the normal-state pseudogap. The theory therefore indicates that the same spin excitation that governs both the normal-state pseudogap-state and SC-state naturally leads to the exotic features of the low-energy electronic structure in the underdoped cuprate superconductors.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"636 ","pages":"Article 1354767"},"PeriodicalIF":1.3,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Planckian bounds from local uncertainty relations","authors":"Zohar Nussinov ,&nbsp;Saurish Chakrabarty","doi":"10.1016/j.physc.2025.1354755","DOIUrl":"10.1016/j.physc.2025.1354755","url":null,"abstract":"<div><div>We introduce “<em>local uncertainty relations</em>” in thermal quantum many-body systems from which fundamental bounds can be derived. These inequalities imply rigorous universal non-relativistic speed limits (independent of interaction range) and, as we focus on in the current work, bounds associated with transport (e.g., the diffusion constant and shear viscosity). Using the chaos bounds and other considerations, we introduce simplified non-rigorous universal transport coefficient inequalities and compare our resulting bounds against experimental data.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"636 ","pages":"Article 1354755"},"PeriodicalIF":1.3,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144623704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectral domain modeling of superconducting slotline in the presence an oblique applied static magnetic field","authors":"Jolly Andrews ,&nbsp;Remya U.D. ,&nbsp;Ajith Ramachandran ,&nbsp;Joseph V.P. ,&nbsp;Vincent Mathew","doi":"10.1016/j.physc.2025.1354743","DOIUrl":"10.1016/j.physc.2025.1354743","url":null,"abstract":"<div><div>The electromagnetic response of a high temperature superconducting (HTS) slotline placed in a static magnetic field at varying oblique angles is analyzed using propagation parameters computed by spectral domain method (SDM). The modified two-fluid theory formulated by Coffey and Clem (CC) for the angular dependence is employed to self-consistently determine the vortex dynamical response of the HTS films made of different material purities. The impedance matrix of the slotline obtained using SDM is modified by incorporating the HTS contribution and Galerkin technique is used for the calculation of the propagation parameters. The paper presents the angular dependence of the obliquely angled static magnetic field on signal propagation and explains the results using vortex dynamic effects.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354743"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of damage and critical current degradation behaviors of RRP and PIT Nb3Sn wires under transverse pressure","authors":"He Ding ,&nbsp;Lintao Li ,&nbsp;Qian Li ,&nbsp;Yuanwen Gao","doi":"10.1016/j.physc.2025.1354751","DOIUrl":"10.1016/j.physc.2025.1354751","url":null,"abstract":"<div><div>The state-of-the-art Nb₃Sn wire still exhibits discrepancies in both mechanical and superconducting critical properties when juxtaposed with the target of the requirement for superconducting wire set for future circular colliders (FCC). Intensive efforts are currently underway to develop high performance Nb₃Sn wires with enhanced mechanical and superconducting properties. In parallel, developing convenient and efficient numerical methods for comprehensively evaluating the mechanical and superconducting properties of various Nb₃Sn wires is of critical significance. Given the relevant context, the analysis of critical current degradation and fracture damage behavior of Nb₃Sn superconducting wires under transverse pressure is of significant importance. In this paper, the detailed strand numerical models are established based on the meso‑structure characteristics of Restacked-Rod-Process (RRP) and Powder-in-tube (PIT) Nb₃Sn wires at first. These models can be used to simulate stress distribution and mechanical behaviors under various external loading conditions. Subsequently, the damage and superconducting critical current degradation of epoxy-impregnated RRP and PIT wires under transverse pressure are evaluated in numerical simulations, taking into account the irreversible degradation caused by the residual plastic stress of the annealed copper matrix. This numerical method encodes all superconducting filaments/sub-elements of the two-dimensional numerical model by considering the periodic positional changes of the twisted filaments/sub-elements along the wire axis. The results indicate that within a transverse pressure range of 100 to 200 MPa, the plastic residual stress of the copper matrix is the primary cause of irreversible critical current degradation. At transverse pressure exceeding 200 MPa, the influence of damage on the critical current cannot be ignored due to the emergence of damage. When the transverse pressure reaches 413 MPa, through-thickness damage has occurred in the Nb₃Sn phase of all types RRP and PIT wires. Compared to PIT B215 wires, the critical current of RRP 108/127 wires have better strain tolerance. The numerical method with a low computational burden in this paper can conveniently evaluate the fracture and damage as well as degradation of critical properties of various Nb₃Sn wires under transverse pressure.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354751"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electromagnetic analysis of coated conductors with ferromagnetic substrates: Novel insights","authors":"Vladimir Sokolovsky ,&nbsp;Leonid Prigozhin","doi":"10.1016/j.physc.2025.1354765","DOIUrl":"10.1016/j.physc.2025.1354765","url":null,"abstract":"<div><div>Ferromagnetic substrates can significantly influence the electromagnetic response of a coated conductor to an external magnetic field and transport current. This study analyzes this response theoretically using the thin shell integrodifferential model. First, assuming the substrate is strongly magnetic and the superconductor is in the Meissner state, we present the analytical solution in a convenient explicit form. This helps us to analyze the superconducting current density distributions, highlighting their differences from those in conductors with non-magnetic substrates. Second, we consider a superconducting layer characterized by a nonlinear current-voltage relation and a substrate with a finite field-independent magnetic permeability. We use an effective spectral numerical method to study the unique features of this hybrid superconductor/ferromagnet system, such as magnetization in a parallel external field and the peculiar nonmonotonic variation of loss observed when alternating transport current and parallel field are applied simultaneously. Dynamic losses for the case of a direct transport current and an alternating parallel field are also investigated. It is shown that tuning the phase and amplitude of the applied parallel field relative to those of the transport current can reduce AC losses.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354765"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of the Halbach permanent magnet guideway in HTS maglev based on sensitivity analysis","authors":"Tianyu Xing ,&nbsp;Jinkai Zhang ,&nbsp;Yan Li ,&nbsp;Can Peng ,&nbsp;Peiyu Yin ,&nbsp;Zigang Deng","doi":"10.1016/j.physc.2025.1354761","DOIUrl":"10.1016/j.physc.2025.1354761","url":null,"abstract":"<div><div>As an important part of the high-temperature superconducting (HTS) maglev system, the performance and stability of the permanent magnet guideway (PMG) is directly related to the loading capacity and safe operation of the HTS maglev train. Therefore, it is necessary to carry out optimization research on the performance of PMG. At present, PMG optimization studies are mostly from the perspective of magnetic circuit, and seldom considered from the perspective of statistical analysis. In this paper, a PMG optimization method based on sensitivity analysis is discussed. First, the PMG dataset is established by simulation with parametric sweeping method. Then, the influence of permanent magnet (PM) dimension and grade on the electromagnetic force of HTS maglev system is investigated using sensitivity analysis method. And the optimization suggestions for the HTS maglev system are given. Finally, the optimization method is applied to present a PMG optimization case, and the optimization results show that the maximum vertical magnetic field is increased by 16.57 %, the maximum lateral magnetic field is increased by 10.97 %, the levitation force of the HTS bulks is increased by 3.23 %, and the guidance force is increased by 11.78 %.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354761"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The inhomogeneous flow behavior of in iron-based superconducting tape production: Formation mechanism and impact on transport performance","authors":"Meng Han ,&nbsp;Chao Yao ,&nbsp;Dongliang Wang ,&nbsp;He Huang ,&nbsp;Chiheng Dong ,&nbsp;Xianping Zhang ,&nbsp;Yanwei Ma","doi":"10.1016/j.physc.2025.1354764","DOIUrl":"10.1016/j.physc.2025.1354764","url":null,"abstract":"<div><div>Iron-based superconductors (IBSs) have emerged as promising candidates for high-field applications, with various IBS wires and tapes developed through advanced fabrication techniques. However, the inhomogeneity of superconducting cores in practical conductors remains a persistent challenge, prevalent in nearly all types of powder-in-tube (PIT) superconducting tapes and significantly degrading both transport performance and mechanical properties. Here, we investigate the deformation behavior of Ba_xK_1-xFe₂As₂ (BaK122) tapes and elucidate the formation mechanism of non-uniform superconducting cores. By simulating the actual rolling process of Ag-sheathed BaK122 (BaK122/Ag) tapes, we reveal the in-situ flow behavior of the BaK122 core within the tape. The inhomogeneity of the BaK122 core arises from the plastic flow mismatch with the outer sheath during rolling, attributed to the core's lower plasticity compared to the metal sheath. The periodic characteristics of this inhomogeneous distribution are precisely identified. Furthermore, we demonstrate that rolling speed is a critical factor, with reduced rolling velocity alleviating strain rate mismatch. However, excessively low rolling speeds compromise core densification by enhancing horizontal transverse expansion. An optimal rolling velocity exists to balance uniformity and densification of the BaK122 core. Using the BaK122/Ag tape as a model system, we determine and experimentally validate this optimal rolling velocity through a series of studies, particularly via superconducting transport current measurements. Our findings provide essential guidance for achieving uniform fabrication of heterogeneous composites, such as high-temperature superconducting tapes.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354764"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of superconducting magnets for high energy beam transport lines for proton cancer therapy","authors":"Gang He ,&nbsp;Yi Zhu ,&nbsp;Wenjie Yang ,&nbsp;Yu Liang ,&nbsp;Yiqin Lei ,&nbsp;Yanbing Yang ,&nbsp;Pengshan Chang ,&nbsp;Lizhen Ma ,&nbsp;Guangquan Chen ,&nbsp;Kedong Wang ,&nbsp;Xu Zhang ,&nbsp;Kai Wang ,&nbsp;Tianfa Liao","doi":"10.1016/j.physc.2025.1354718","DOIUrl":"10.1016/j.physc.2025.1354718","url":null,"abstract":"<div><div>In proton cancer therapy, to overcome the size and performance limitations of conventional electromagnetic systems, we have designed a superconducting high-energy beam transport line that utilizes superconducting magnets to provide higher magnetic fields, thereby significantly reducing system size and enhancing efficiency. The transport line consists of six groups of superconducting magnets, each employing a discrete cosine theta (DCT) coil structure <span><span>[1]</span></span>, <span><span>[2]</span></span>, <span><span>[3]</span></span>, <span><span>[4]</span></span>, <span><span>[5]</span></span>, comprising one curved dipole magnet and two quadrupole magnets, forming a Q-D-Q (quadrupole-dipole-quadrupole) configuration. The dipole magnet generates a central field of 2.77 T with a bending radius of 900 mm, while the quadrupole magnets have a gradient of 40 T/m. To ensure magnetic field quality, we developed a parametric model in CST and optimized the field characteristics, achieving an integral magnetic field uniformity of better than 0.01%. During rapid excitation, eddy current losses in metallic structures and AC losses in superconductors lead to temperature rise, which may trigger quenching. To mitigate this, we developed a detailed finite element model (FEM) in ANSYS and optimized the magnet’s cooling structure, ensuring that the maximum temperature rise is limited to 0.66 K over three operating cycles. Simultaneously, we established a 2D structural model to analyze the stresses in the magnet, confirming that the Von Mises stress is lower than the yield stress. Through these optimizations, a prototype was successfully fabricated to explore the manufacturing process of the Q-D-Q magnets. This work not only provides a technical foundation for future mass production but also offers critical technical reserves for the construction of superconducting Gantries.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354718"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Pt-Ti thin-film heating method for de-fluxing SFQ circuits in superconducting computers","authors":"Zhichao Chen,&nbsp;Jian Zhou,&nbsp;Lingyun Li,&nbsp;Lixing You","doi":"10.1016/j.physc.2025.1354748","DOIUrl":"10.1016/j.physc.2025.1354748","url":null,"abstract":"<div><div>This paper proposes a Platinum (Pt)-Ti (Titanium) thin-film heating method for de-fluxing Single Flux Quantum (SFQ) circuits, addressing key limitations of conventional hotspot-based approaches, such as non-uniform temperature distribution, low thermal efficiency, and delayed response. A comprehensive analysis and performance evaluation of different heating methods are conducted to investigate the impact of heat methods on Josephson junction (JJ) de-fluxing. Superconducting computers, which use SFQ logic for high-speed operation and ultra-low power consumption, suffer from logical errors caused by trapped magnetic flux in JJs. To de-flux an SFQ circuit after logic errors, the JJs must be heated above the threshold temperature and then cooled in the absence of a magnetic field. Our studies show that heating the JJs to 22 K or above reliably removes trapped flux. Pt thin-film resistive materials, known for their rapid thermal response and controllable diffusion, offer a more efficient solution for de-fluxing and thermal control in SFQ circuits. The thin-film method demonstrates superior performance, achieving a more uniform temperature distribution (standard deviation of 0.02 K), faster thermal response within 1.2 s, and an optimal heating power of 1500 mW with an effective heating duration of 2 s. These results demonstrate a reliable and efficient de-fluxing method, essential for restoring functionality and ensuring logical error recovery in large-scale superconducting computers.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354748"},"PeriodicalIF":1.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Something about the Mechanism of Induction Phenomena: The forgotten work of Berta de Haas-Lorentz on diamagnetism in superconductors","authors":"Giulia Venditti ,&nbsp;Carlo Beenakker ,&nbsp;Louk Rademaker","doi":"10.1016/j.physc.2025.1354762","DOIUrl":"10.1016/j.physc.2025.1354762","url":null,"abstract":"<div><div>In 1925, Dr. Geertruida Luberta “Berta” de Haas-Lorentz published the paper “<em>Iets over het mechanisme van inductieverschijnselen</em>” in the journal <em>Physica</em>. Her paper was the first to discuss perfect diamagnetism of superconductors, eight years before the discovery of the Meissner effect, when the essential difference between the two phenomena was not understood. Unfortunately, her work was almost forgotten by the scientific community. To counter this, we translate her seminal 1925 paper from Dutch into English. We provide an overview of the life of Dr. De Haas-Lorentz, and comment on her pioneering contribution to the theory of superconductivity.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"635 ","pages":"Article 1354762"},"PeriodicalIF":1.3,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144481246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}