Physica C-superconductivity and Its Applications最新文献

{"title":"Electromagnetic characteristics analysis of an improved stator structure for high-temperature superconducting motors","authors":"Zhenyang Zhang ,&nbsp;Yanfei Yang ,&nbsp;Kai Bo","doi":"10.1016/j.physc.2026.1354835","DOIUrl":"10.1016/j.physc.2026.1354835","url":null,"abstract":"<div><div>In high-temperature superconducting (HTS) motor design, using superconducting high-power magnets generates a magnetic field strength far exceeding that of conventional motors. This leads to magnetic circuit saturation. The stator typically uses a combination of non-magnetic teeth and a magnetic yoke, known as an air-gap winding structure. This structure solves the magnetic saturation problem. However, it increases the magnetic reluctance of the motor circuit. It causes issues like severe leakage flux, poor heat dissipation, and low structural strength. To address this, we propose an improved stator structure for HTS motors. It is based on the traditional magnetic material stator structure. It adds magnetic conductors at the stator tooth ends. This paper first presents the improved stator structure. It analyzes the impact of magnetic conductor structural parameters on the motor's magnetic field and performance. Then, particle swarm optimization (PSO) is used to study the torque ripple optimization of the motor with the improved stator structure. Finally, the improved stator structure motor is compared with the original air-gap winding structure motor. This verifies the reliability and superiority of the improved stator structure. The final research results will provide strong support for the development of HTS motors.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"642 ","pages":"Article 1354835"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171536","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":"Simulating abrikosov vortex dynamics to characterize electromagnetic response","authors":"Surbhi Singla","doi":"10.1016/j.physc.2026.1354837","DOIUrl":"10.1016/j.physc.2026.1354837","url":null,"abstract":"<div><div>Abrikosov vortices in mixed-state superconductors are known to pin at material defects and dynamically respond to electromagnetic perturbations. The resulting dynamics are often highly nonlinear and challenging to model. This work introduces a simulation framework based on the Ginzburg-Landau formalism for analyzing vortex-impurity interactions, capable of extending to multiple coupled defects. Results are presented for a single pinned vortex in both cuprate and conventional superconducting thin films. The simulations reveal geometric resonance behavior when the impurity radius is a small integer multiple of the coherence length, with amplitude-dependent transitions from frequency hardening to softening as the impurity radius increases. Using London relations, the corresponding electromagnetic response was quantified, showing depinning thresholds approaching the nanotesla and microvolt-per-meter regime and narrowband characteristics with quality factors on the order of <span><math><msup><mrow><mn>10</mn></mrow><mn>4</mn></msup></math></span>. Residual and empirical analyses confirm that the framework is numerically stable, physically consistent, and computationally efficient, providing a foundation for future studies of engineered vortex dynamics and their electromagnetic applications.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"642 ","pages":"Article 1354837"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171537","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":"Effect of winding pitches on screening current induced field of CORC cables","authors":"Jian Cheng ,&nbsp;Zhiyi Luo ,&nbsp;Fengyin Zhang ,&nbsp;Weili Zhao ,&nbsp;Quan Zhang ,&nbsp;Bangzhu Wang ,&nbsp;Junhua Cheng","doi":"10.1016/j.physc.2026.1354836","DOIUrl":"10.1016/j.physc.2026.1354836","url":null,"abstract":"<div><div>Conductor on round core (CORC) cables exhibit great potential for applications in large-scale high-field magnets of fusion and power transmission due to their high mechanical flexibility and large current capacity. However, both the ripple current in power transmission systems and the excitation/demagnetization processes in magnet applications inevitably generate alternating magnetic fields perpendicular to the tape surface. These fields induce screening currents and corresponding screening current induced field (SCIF) on the wide face of the tapes, which degrade the magnetic field uniformity and even mechanical or thermal stability in large-scale magnet applications. In this paper, a finite element numerical simulation based on the <em>T</em>–<em>A</em> formulation is employed to investigate the SCIF characteristics of CORC cables with different winding pitches at 77 K, 20 K, and 4.2 K. The numerical results show that the amplitude of the SCIF increases significantly with the ramp rate of the applied magnetic field. Moreover, both the peak and steady-state values of the SCIF increase notably with the winding pitch, exhibiting a clear monotonic trend. This study reveals the influence of winding pitches on the SCIF characteristics of CORC cables and provides a valuable reference for the structural optimization of conductors in large-scale high-field magnets.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"642 ","pages":"Article 1354836"},"PeriodicalIF":1.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146070760","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":"Temperature equalization control method for rotor magnet of HTS synchronous condenser with circulating cold helium gas","authors":"Xin Chen ,&nbsp;Lei Wang ,&nbsp;Cong Wang ,&nbsp;Shixian Liu ,&nbsp;Jianhua Liu ,&nbsp;Gongxuan Chen ,&nbsp;Hui Wang ,&nbsp;Huangfang Wu ,&nbsp;Jiancheng Zhang ,&nbsp;Qiuliang Wang","doi":"10.1016/j.physc.2025.1354825","DOIUrl":"10.1016/j.physc.2025.1354825","url":null,"abstract":"<div><div>In the cooling system of high-temperature superconducting (HTS) synchronous condenser rotor magnets, cold helium gas serves as the primary cooling medium. The complex coupling relationships among its flow rate, temperature, and pressure require precise control to address the instability caused by localized hotspots in the superconducting magnets.This paper integrates the singular perturbation control theory of variable-domain Smith to construct a mathematical model of the cold helium gas circulating cooling system.The cold helium gas circulation cooling system is decomposed into fast and slow subsystems. By precisely controlling the flow rate and velocity of the cold helium gas, the goal of eliminating local hotspots and achieving uniform temperature distribution in the superconducting magnet is realized.Simultaneously, the system performance is optimized using fuzzy adaptive PID control.In addition, a simulation experiment was conducted on the cold helium gas circulation cooling system of the superconducting magnet using this method, which verified the effectiveness of the aforementioned approach in eliminating local hotspots and improving temperature uniformity.This study provides an engineering-feasible optimization scheme for the cryogenic thermal management of the rotor magnet in HTS synchronous condensers.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"641 ","pages":"Article 1354825"},"PeriodicalIF":1.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145852452","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":"Multi-parameter optimization of SPS conditions for high-performance MgB2: A statistical approach","authors":"Hasan Ağıl","doi":"10.1016/j.physc.2026.1354831","DOIUrl":"10.1016/j.physc.2026.1354831","url":null,"abstract":"<div><div>Spark Plasma Sintering (SPS) temperature critically governs the microstructural development and superconducting performance of MgB₂ bulk superconductors. In this study, MgB₂ bulks were fabricated at different SPS temperatures, and their density, porosity, grain size, critical current density (<em>J_c</em>), and magnetic levitation properties were systematically evaluated. To move beyond conventional qualitative interpretations, Pearson correlation analysis, multiple linear regression, and principal component analysis (PCA) were jointly employed to quantitatively assess the relative and competing effects of microstructural parameters on <em>J_c</em>. The results demonstrate that densification is the dominant parameter controlling <em>J_c</em> at 20 K, exhibiting a strong positive correlation with superconducting and levitation performance, while porosity acts as the primary detrimental factor. Grain growth shows a secondary limiting effect by reducing flux pinning efficiency at higher sintering temperatures. Multiple linear regression confirms density as the most influential predictor of <em>J_c</em>. In contrast, PCA reveals that SPS temperature, density, and <em>J_c</em> cluster along a common high-performance axis, distinct from grain size–related mechanisms. These findings provide a quantitative, data-driven framework for understanding SPS-induced performance optimization in MgB₂ and offer broader insights into processing–structure–property relationships in bulk superconductors.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"641 ","pages":"Article 1354831"},"PeriodicalIF":1.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979114","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":"Energy conservation and reversibility during thermodynamic changes of state in superconductors: Joule heat vs. magnetocaloric cooling","authors":"Andreas Schilling","doi":"10.1016/j.physc.2026.1354832","DOIUrl":"10.1016/j.physc.2026.1354832","url":null,"abstract":"<div><div>In the Meissner phase of a superconductor, an external constant magnetic field is shielded by circulating persistent zero-resistance supercurrents that are formed by Cooper pairs. However, a thermodynamic change of state within this phase, such as cooling or heating, inevitably generates normal currents of thermally excited unpaired charge carriers, induced by the time-dependent variations in the local magnetic field. They not only lead to deviations of the magnetic-field distribution from textbook Meissner profiles but also cause dissipative Joule heating. This sharply contradicts the expected reversibility of a truly thermodynamic superconducting state, a fact that has largely been overlooked in the literature. We show that these normal currents also produce a magnetocaloric cooling, which in total instantaneously and precisely compensates for the dissipated heat, thus ensuring overall energy conservation and reversibility. However, the Joule heating and magnetocaloric cooling processes are spatially distinct and should therefore lead to temperature inhomogeneities. We quantify these effects assuming realistic material parameters and conclude that they are challenging to measure with current experimental techniques. Significant temperature gradients are expected only directly at the first-order transition to the superconducting state, where the discontinuous flux expulsion should induce normal currents that are much larger than those deep in the Meissner phase. We also argue that the underlying physics in superconductors is fundamentally identical to that of thermomagnetic generators, where electromechanical work can be extracted from magnetized matter subjected to thermal cycles, and where the magnetocaloric cooling is balanced by the heat supplied from an external thermal reservoir.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"641 ","pages":"Article 1354832"},"PeriodicalIF":1.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023203","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":"Near-Tc vortex pinning and Dew–Hughes scaling in CaK(Fe1−xNix)4As4 and Ba(Fe1−xCox)2As2 single crystals","authors":"N. Haberkorn ,&nbsp;M. Xu ,&nbsp;J. Schmidt ,&nbsp;S.L. Bud’ko ,&nbsp;P.C. Canfield","doi":"10.1016/j.physc.2026.1354834","DOIUrl":"10.1016/j.physc.2026.1354834","url":null,"abstract":"<div><div>We compare pinning-force scaling in Fe-based superconductors exhibiting moderate vortex fluctuations using the Dew-Hughes formalism. Single crystals of CaK(Fe_1−xNi_x)₄As₄ (1144) and Ba(Fe_1−xCo_x)₂As₂ (122) are analyzed by fitting the normalized pinning force, <span><math><mrow><msub><mi>F</mi><mi>p</mi></msub><mo>/</mo><msub><mi>F</mi><mrow><mi>p</mi><mo>,</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>=</mo><mi>A</mi><msup><mrow><mi>h</mi></mrow><mi>p</mi></msup><msup><mrow><mo>(</mo><mrow><mn>1</mn><mo>−</mo><mi>h</mi></mrow><mo>)</mo></mrow><mi>q</mi></msup></mrow></math></span>, as a function of the reduced field <span><math><mrow><mi>h</mi><mo>=</mo><mi>H</mi><mo>/</mo><msub><mi>H</mi><mrow><mi>i</mi><mi>r</mi><mi>r</mi></mrow></msub><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> near <em>T_c</em>, with the peak position at <span><math><mrow><msub><mi>h</mi><mn>0</mn></msub><mo>=</mo><mi>p</mi><mo>/</mo><mrow><mo>(</mo><mrow><mi>p</mi><mo>+</mo><mi>q</mi></mrow><mo>)</mo></mrow></mrow></math></span>. In 1144, <span><math><mrow><msub><mi>F</mi><mi>p</mi></msub><mrow><mo>(</mo><mi>h</mi><mo>)</mo></mrow></mrow></math></span> data are well described by single-peak scaling with <em>h₀</em> ≃ 0.30–0.34, consistent with predominant point-like disorder. In 122, <em>h₀</em> shifts from ≈ 0.17–0.23 in underdoped crystals and to ≈ 0.37–0.40 near optimal doping, indicating a mixed δ<em>T_c</em>/point pinning landscape. Literature datasets show that proton irradiation in lightly doped 1144 preserves a single peak near <em>h₀</em> ≈ 0.33, whereas heavy-ion irradiation in near-optimally doped 122 produces a high-field shoulder. Overall, Dew-Hughes scaling captures the main trends phenomenologically and provides a practical map linking the effective peak position <em>h₀</em> to the prevailing pinning landscape.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"641 ","pages":"Article 1354834"},"PeriodicalIF":1.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023692","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":"Vortex matter in labyrinthine configurations","authors":"K. Rojas-Daza ,&nbsp;J. Barba-Ortega ,&nbsp;C.A. Aguirre ,&nbsp;Clarence Cortés ,&nbsp;P. Díaz ,&nbsp;David Laroze","doi":"10.1016/j.physc.2026.1354833","DOIUrl":"10.1016/j.physc.2026.1354833","url":null,"abstract":"<div><div>In this work, we investigate numerically the vortex dynamics in thin superconducting films patterned with labyrinthine geometries using numerical solutions of the time-dependent Ginzburg–Landau equations (<span><math><mi>TDGL</mi></math></span>). We analyzed three complementary scenarios: (i) in the absence of an external magnetic field (<span><math><mrow><mi>H</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>0</mn></mrow></math></span>) under an applied direct current (<span><math><mi>J</mi></math></span>) and (ii) in the absence of an applied current (<span><math><mrow><mi>J</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>0</mn></mrow></math></span>) but under an external magnetic field (<span><math><mi>H</mi></math></span>) and finally (iii) in the absence of an external magnetic field (<span><math><mrow><mi>H</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>0</mn></mrow></math></span>) under an applied current with negative and positive polarity while varying the Ginzburg–Landau parameter (<span><math><mrow><mi>κ</mi><mo>=</mo><mn>2</mn><mo>.</mo><mn>0</mn><mo>,</mo><mn>3</mn><mo>.</mo><mn>0</mn><mo>,</mo><mn>4</mn><mo>.</mo><mn>0</mn><mo>,</mo><mn>5</mn><mo>.</mo><mn>0</mn><mo>,</mo><mn>6</mn><mo>.</mo><mn>0</mn></mrow></math></span>). By generating maze-like domains through a randomized Kruskal algorithm and sweeping the applied magnetic field <span><math><mi>H</mi></math></span>, we determine the magnetization <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>z</mi></mrow></msub></math></span> and extract the first critical field <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>. Our simulations reveal a pronounced dependence of <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> on the underlying geometry of the labyrinth, showing that the intricate network of corridors significantly modifies the onset of vortex penetration. Current–voltage measurements obtained from the dynamics of <span><math><mi>TDGL</mi></math></span> reveal a clear variation in the critical current with the Ginzburg–Landau parameter (<span><math><mi>κ</mi></math></span>), highlighting the roles of coherence length and penetration depth in these confined structures. Despite the intentional breaking of spatial symmetry by the maze design, no superconducting diode effect is observed within the explored parameter space. Smaller labyrinth sections showed nearly zero magnetic penetration, preserving superconductivity at higher fields in agreement with Bean–Livingston barrier behavior.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"641 ","pages":"Article 1354833"},"PeriodicalIF":1.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023691","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":"Foreword for the special issue of Physica C “Quantum Matter” dedicated to Jan Zaanen","authors":"","doi":"10.1016/j.physc.2025.1354822","DOIUrl":"10.1016/j.physc.2025.1354822","url":null,"abstract":"","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"640 ","pages":"Article 1354822"},"PeriodicalIF":1.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925964","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":"Robust s±-wave pairing in a bilayer two-orbital model of pressurized La3Ni2O7 without the γ Fermi surface","authors":"Yi Gao","doi":"10.1016/j.physc.2025.1354824","DOIUrl":"10.1016/j.physc.2025.1354824","url":null,"abstract":"<div><div>We studied the superconducting pairing symmetry based on a newly constructed tight-binding model of La<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Ni<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>7</mn></mrow></msub></math></span> under pressure, where the <span><math><mi>γ</mi></math></span> band sinks below the Fermi level and does not form the Fermi surface. The superconducting pairing symmetry is <span><math><msub><mrow><mi>s</mi></mrow><mrow><mo>±</mo></mrow></msub></math></span>-wave and is robust against the variation of the interaction strength. In this model, although the <span><math><mi>γ</mi></math></span> and <span><math><mi>δ</mi></math></span> bands are away from the Fermi level, the superconducting pairing function on them is not tiny. Instead, since the top of the <span><math><mi>γ</mi></math></span> band and bottom of the <span><math><mi>δ</mi></math></span> band are both located at <span><math><mo>∼</mo></math></span>500 meV away from the Fermi level, and they are almost nested by the peak structure in the spin fluctuation, thus by forming an anti-phase pairing function on them, these two bands act constructively to superconductivity. Finally with detailed derivation and numerical calculation, we demonstrate that the Fermi surface approximated Eliashberg equation may lead to deviation of the pairing symmetry.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"640 ","pages":"Article 1354824"},"PeriodicalIF":1.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788353","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}