Physica C-superconductivity and Its Applications最新文献

{"title":"Simulation and analysis of a superconducting switch based on Josephson array","authors":"Hai Wang ,&nbsp;Jiajun Chen ,&nbsp;Yifan Wu ,&nbsp;Wenqi Wu ,&nbsp;Zhidan Zhang ,&nbsp;Xiangyan Kong","doi":"10.1016/j.physc.2024.1354644","DOIUrl":"10.1016/j.physc.2024.1354644","url":null,"abstract":"<div><div>Superconducting transition edge sensors (TES) have been applied to a variety of astronomical detection systems. To improve their detection efficiency, superconducting switches are essential components in time-division multiplexing systems. However, flux-actuated superconducting switches have such problems as large area, high noise, and complex operation. This paper proposes a structure of non-hysteresis Josephson junction array with RL transmission unit to realize a superconducting switch. Firstly, based on the current equation of the Josephson junction, a PSPICE model of a superconducting switch was established. Then, the optimization design of a single junction switch transmitting a 100 MHz signal was analyzed. Finally, we analyzed how to suppress high-frequency noise when transmitting signals above 1 GHz. Since the signal of the Josephson junction array switch is directly read out by the SQUID, it has the advantage of reducing the switch area and operation complexity.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"629 ","pages":"Article 1354644"},"PeriodicalIF":1.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183622","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":"Rapid vortex flux motion in GdBa2Cu3O7−d nanobridges","authors":"L.E. Díaz ,&nbsp;N. Haberkorn","doi":"10.1016/j.physc.2025.1354649","DOIUrl":"10.1016/j.physc.2025.1354649","url":null,"abstract":"<div><div>We report on the vortex dynamics of a GdBa₂Cu₃O_7−δ nanobridge through current-voltage measurements. The study is conducted on a sample with a length of 10 μm, a width of 0.62 μm, and a thickness of 80 nm, which was grown by sputtering and fabricated using a two-step process: first, optical lithography, followed by focused ion beam milling. The results show that the film exhibits a low critical current density but demonstrates high vortex flux motion. From the Larkin–Ovchinnikov instability, we extract velocities exceeding 10 km/s at low temperatures and fields around 0.4 T (with nearly 10 vortices crossing the bridge width) and approximately 3 km/s for fields around 5 T. These results are compared with recent publications reporting high vortex velocities.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"629 ","pages":"Article 1354649"},"PeriodicalIF":1.3,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182558","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":"Minimal surfaces & the intermediate state of type-I superconductors","authors":"Pavol Valko ,&nbsp;Thomas A. Girard","doi":"10.1016/j.physc.2024.1354641","DOIUrl":"10.1016/j.physc.2024.1354641","url":null,"abstract":"<div><div>The geometry of the intermediate state (IS) flux structures in type-I superconductors, observed during early stages of magnetic flux penetration induced by an externally applied perpendicular magnetic field, is analysed using the concept of minimal surfaces. This approach is based on the assumption that local free energy minimization, for each individual flux structure, dominates when the magnetic flux regions are sufficiently spatially separated; that is, when the global free energy minimization predicts very low periodicity in the intermediate state of the sample.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"629 ","pages":"Article 1354641"},"PeriodicalIF":1.3,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183621","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":"Synthesis and characterization of YBCO superconducting thin films doped with BaHfO3 via the TFA-MOD technique for potential aerospace applications","authors":"Murat Bektas ,&nbsp;Isil Birlik ,&nbsp;Erdal Celik","doi":"10.1016/j.physc.2024.1354633","DOIUrl":"10.1016/j.physc.2024.1354633","url":null,"abstract":"<div><div>The study aims to improve the critical current density (<em>J_c</em>) and flux pinning of YBa₂Cu₃O_7-δ (YBCO) high-temperature superconducting films. The decline in <em>J_c</em> at high temperatures and magnetic fields is due to intrinsic crystalline anisotropy, thermal fluctuations, and lack of effective pinning centers. To tackle this, the study uses a novel approach by incorporating BaHfO₃ (BHO) nanostructures (dots, rods, or particles) as artificial pinning centers in YBCO films. The objective is to augment critical current density and enhance flux pinning properties using trifluoroacetates metal organic deposition method (TFA-MOD) on SrTiO₃ (STO) substrates, with a specific focus on applications in the aerospace industry. Characterization of YBCO solutions involves measuring contact angle, viscosity, and modulus. Thermal, structural, microstructural and superconducting properties of the films were scrutinized by Differential Thermal Analysis-Thermogravimetry (DTA-TG), Fourier Transform Infrared (FTIR), X-ray diffractometry (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) and Atomic Force Microscopy (AFM), Surface Profilometer (SP) and Physical Property Measurement System (PPMS). Rheological tests show viscosity decreases with temperature before stabilizing. Undoped YBCO exhibits good wetting on STO substrates. Heat treatment involves organic solvent removal and TFA decomposition, with FTIR and XRD analyses confirming decomposition of acetate complexes and strong c-axis texture. XPS results indicate consistent chemical compositions, while surface morphologies are flat and crack-free, with denser structures in BHO-doped films. Doping improves superconductivity up to a certain concentration, after which it decreases. Average film thickness is around 240 nm. Undoped YBCO films exhibit poor superconducting properties due to secondary phases, while BHO doping influences superconductivity, with an increase in critical current density up to a certain concentration, beyond which superconductivity is lost.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"629 ","pages":"Article 1354633"},"PeriodicalIF":1.3,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183619","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":"Superconducting DC busbar with low resistive joints for all-electric aircraft propulsion system","authors":"Gaurav Gautam ,&nbsp;Min Zhang ,&nbsp;Weijia Yuan ,&nbsp;Graeme Burt ,&nbsp;Daniel Malkin","doi":"10.1016/j.physc.2024.1354617","DOIUrl":"10.1016/j.physc.2024.1354617","url":null,"abstract":"<div><div>High-temperature superconductors (HTS) can carry high currents with almost zero loss when transmitting direct current (DC). Their compact size and lower weight make them suitable for the application of all-electric aircraft. However, the current carrying capability of a single HTS tape is limited to a few hundred amps; therefore, for high-current applications, multiple HTS tapes need to be connected in parallel. The flat geometry of HTS tape and its critical current (IC) dependence on strain complicate grouping them in parallel. Furthermore, the length of HTS tape is limited by its crystal structure, necessitating low-resistance joints for extended applications. A superconducting busbar design for high-current applications is developed and tested to address these challenges. The superconducting busbar is designed in a way that it helps to reduce the effect of the self-field on critical current and also ride through the fault events. Yttrium barium copper oxide (YBCO) tapes are used to develop the busbar prototype, tested against DC currents in a liquid nitrogen environment. Joint optimization is carried out to determine the required length for efficiently joining HTS tapes. Two busbar prototypes are developed with 180° and 90° joints to join 5 HTS tapes and tested in self-field. A joint resistance of 100 <em>n</em>Ω is measured at self-field for the 180° joint busbar, and 800 <em>n</em>Ω is measured for the 90° joint busbar. Both busbar prototypes are subjected to power cycling and thermal cycling to assess joint performance in self-field and any degradation of the joint electrical parameters during testing.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"627 ","pages":"Article 1354617"},"PeriodicalIF":1.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744361","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":"Development and experiment of superconducting Eddy current braking prototype device","authors":"Wenhua Dai ,&nbsp;Weibin Xi ,&nbsp;Chao Fang ,&nbsp;Jing Wei ,&nbsp;Shuangsong Du ,&nbsp;Rui Hu ,&nbsp;Zhengbao Yu","doi":"10.1016/j.physc.2024.1354619","DOIUrl":"10.1016/j.physc.2024.1354619","url":null,"abstract":"<div><div>An experimental superconducting eddy current braking prototype was designed, constructed and thoroughly evaluated. The components of the apparatus were accurately described, and heat leakage was calculated. The results showed that the heat leakage was 0.53 W at 5 K and 19.2 W at 40 K. The selected cryogenic system met the operational requirements of the apparatus. The fabrication process was outlined, and the apparatus was tested with the integrated cryogenic system. The device successfully cooled to the target temperature. The circular coil, carrying a current of 180 A, generated a braking force of 0.7 kN at a speed of 400 km/h, while the racetrack coil, at 50 A, produced 0.15 kN at the same speed. The experimental results were consistent with the analysis, demonstrating the successful operation of the prototype throughout the testing phase.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"629 ","pages":"Article 1354619"},"PeriodicalIF":1.3,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183620","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":"Does the Meissner effect violate the second law of thermodynamics?","authors":"J.E. Hirsch","doi":"10.1016/j.physc.2024.1354618","DOIUrl":"10.1016/j.physc.2024.1354618","url":null,"abstract":"<div><div>In Entropy 24, 83 (2022) (Nikulov 2022), titled “The Law of Entropy Increase and the Meissner Effect”, its author Alexey Nikulov argues that the Meissner effect exhibited by type I superconductors violates the second law of thermodynamics. Contrary to this claim, I show that the Meissner effect is consistent with the second law of thermodynamics provided that a mechanism exists for the supercurrent to start and stop without generation of Joule heat. The theory of hole superconductivity provides such a mechanism, the conventional theory of superconductivity does not. It requires the existence of hole carriers in the normal state of the system.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"629 ","pages":"Article 1354618"},"PeriodicalIF":1.3,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comment on “Magnetic flux trapping in hydrogen-rich high-temperature superconductors” by V.S. Minkov, V. Ksenofontov, S.L. Bud’ko, E.F. Talantsev and M.I. Eremets, Nat. Phys. 19, 1293 (2023)","authors":"N. Zen","doi":"10.1016/j.physc.2024.1354614","DOIUrl":"10.1016/j.physc.2024.1354614","url":null,"abstract":"<div><div>In the paper, Minkov et al. (2023), Eremets et al. present experimental results for flux creep measurements using H₃S under high pressure in a diamond anvil cell, the pioneering material for the era of hydride superconductivity, with the aim of providing evidence that magnetic flux is trapped in H₃S under high pressure and that persistent currents are circulating there. Initially, it was thought that the measurements started immediately after switching off the applied magnetic field, as indicated by the labeling of the horizontal axis of Fig. 4c of Ref. Minkov et al. (2023). However, it was revealed in private communications by Eremets et al. to the author and in a later paper by Bud’ko et al. (2024) <span><span>[1]</span></span> that there was a large delay time in starting the flux creep measurements. If that is the case, the measurement period of <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> s or <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup></mrow></math></span> s as shown in Fig. 4c is too short to draw any conclusions about flux creep, or even to determine whether flux creep was being measured.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"628 ","pages":"Article 1354614"},"PeriodicalIF":1.3,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The fabrication of graphene supported Ni nanoparticles and its doping influence on the microstructure and superconductivity of MgB2","authors":"Qian Zhao ,&nbsp;Shilong Ma ,&nbsp;Guoqing Xia ,&nbsp;Jiabo Zhang ,&nbsp;Yaran Zhang","doi":"10.1016/j.physc.2024.1354615","DOIUrl":"10.1016/j.physc.2024.1354615","url":null,"abstract":"<div><div>A highly dispersed Ni nanoparticle supported on a graphene matrix (nano-Ni/G) has been successfully synthesized using a novel chemical reduction process to overcome agglomeration in traditional MgB₂ preparation methods. The influence of the reduction technique on nanoparticle size and structure was thoroughly investigated using a model system. The resulting nanoparticles were small enough (10 nm) to decorate the 2D graphene layers as sandwich structures. This unique morphology contributes to providing more effective flux pinning centers by forming tiny MgNi_2.5B₂ and efficiently substituting C for B in MgB₂ bulks through the principle of double action. Moreover, the low-melting eutectic liquid formed by Mg-Ni at 506 °C is beneficial for the fast fabrication of well-connected MgB₂ at low temperatures. Furthermore, a small enhancement of critical current density (<em>J_c</em>) was observed in the doped sample with respect to the undoped ones. However, the advantages of the as-prepared nanoparticles were greatly suppressed by the large presence of MgO during the deposition process, leading to lower superconducting performance than undoped MgB₂ bulks. Based on the analysis, further investigation should focus on inducing more flux pinning centers by controlling impurities during the deposition process for achieving optimal performance.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"627 ","pages":"Article 1354615"},"PeriodicalIF":1.3,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651138","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":"Spin fluctuations in conventional superconductors and anomalous isotope effect in PdH and PdD","authors":"J. Rivera,&nbsp;A. Rubio-Ponce","doi":"10.1016/j.physc.2024.1354602","DOIUrl":"10.1016/j.physc.2024.1354602","url":null,"abstract":"<div><div>Spin fluctuations have been suggested to be an influence to the superconducting phenomenon, either favorably or disruptively. Consequently, we study the role of magnons in the thermodynamics of conventional superconductors proposing a relationship between magnetization and electron-magnon coupling (<span><math><msub><mrow><mi>λ</mi></mrow><mrow><mi>e</mi><mi>m</mi></mrow></msub></math></span>) for vanadium, niobium, lead, palladium, and the PdX (where <span><math><mrow><mi>X</mi><mo>=</mo></mrow></math></span> hydrogen, deuterium, and tritium) systems. We suggest a different relationship for the Coulomb pseudopotential (<span><math><msubsup><mrow><mi>μ</mi></mrow><mrow><mi>N</mi></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span>), which is influenced by the characteristic frequency (<span><math><msub><mrow><mi>ω</mi></mrow><mrow><mo>ln</mo></mrow></msub></math></span>). In this way, the critical temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>) of the elements studied and the PdX compounds are very close to those reported experimentally. The PdH, PdD and PdT compounds have shown critical temperatures of 9.05 K, 12.20 K and 12.90 K, respectively. Finally, we determine the behavior of <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> for PdX under hydrostatic pressures up to 10 GPa, showing an alternative explanation for the anomalous isotope effect in PdH and PdD compounds. Our study was carried out by numerically solving the linearized Migdal-Eliashberg equations coupling the Bogoliubov-de-Gennes method, while the magnetic excitation was calculated using linear response time dependent within the Density Functional Theory, framework, both implemented in the Elk code.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"627 ","pages":"Article 1354602"},"PeriodicalIF":1.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554182","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}