Physica C-superconductivity and Its Applications最新文献

{"title":"First-principles analysis of superconducting magnesium diboride under pressure using the Cooper pair distribution function Dcp(ω,Tc)","authors":"J.A. Camargo-Martínez ,&nbsp;G.I. González-Pedreros ,&nbsp;C. Vázquez-López","doi":"10.1016/j.physc.2025.1354677","DOIUrl":"10.1016/j.physc.2025.1354677","url":null,"abstract":"<div><div>The Cooper pair distribution function <span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub><mrow><mo>(</mo><mi>ω</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> is employed to analyze the behavior of the MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> superconductor under pressures ranging from 8 to 32 GPa. The results of <span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub><mrow><mo>(</mo><mi>ω</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> indicate that the formation of Cooper pairs in this compound is highly probable within the energy interval 0–35 meV, where significant vibrational contributions to phonon dispersion arise from both Mg and B atoms. Moreover, the parameters <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>N</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub></math></span> obtained from <span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub><mrow><mo>(</mo><mi>ω</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> accurately replicate the pressure dependence of the superconducting critical temperature T<span><math><msub><mrow></mrow><mrow><mi>c</mi></mrow></msub></math></span> observed in MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>. This provides a possible phenomenological explanation for its highest experimentally measured T<span><math><msub><mrow></mrow><mrow><mi>c</mi></mrow></msub></math></span>. An electronic analysis of <span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub><mrow><mo>(</mo><mi>ω</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> function below the Fermi level reveals initial consistency with both theoretical and experimental results for the superconducting gap energy in MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>. These findings demonstrate that <span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>c</mi><mi>p</mi></mrow></msub><mrow><mo>(</mo><mi>ω</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> is a promising theoretical tool for studying conventional superconductors.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"632 ","pages":"Article 1354677"},"PeriodicalIF":1.3,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621485","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 significance of “stripes” in the physics of the cuprates, the Hubbard model, and other highly correlated electronic systems","authors":"Thomas P. Devereaux ,&nbsp;Steven A. Kivelson","doi":"10.1016/j.physc.2025.1354683","DOIUrl":"10.1016/j.physc.2025.1354683","url":null,"abstract":"<div><div>“Stripes”— meaning unidirectional charge-density-waves, sometimes (but not always) accompanied by spin-density-waves with twice the period - are now known to arise in broad swathes of the cuprate phase diagram, and appear as a strong ordering tendency in numerical studies of Hubbard-like models of highly correlated electron systems. Jan Zaanen’s work played a seminal role in predicting their existence, and exploring their possible significance. They are <em>not</em> related to any weak-coupling physics associated with some form of Fermi-surface nesting. And whether one likes them or not, they are surprisingly difficult to avoid; in the Hubbard model, for example, they often appear as an alternative order that can out-compete the otherwise favored <span><math><mi>d</mi></math></span>-wave superconductivity.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"632 ","pages":"Article 1354683"},"PeriodicalIF":1.3,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562705","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":"Effects of extrinsic parameters on superconducting nanowire single-photon detector output – A study towards developing read-out circuit","authors":"Amit Soni ,&nbsp;Anish M. Bhargav ,&nbsp;Pratiksha Pratap ,&nbsp;V.N. Singh","doi":"10.1016/j.physc.2025.1354689","DOIUrl":"10.1016/j.physc.2025.1354689","url":null,"abstract":"<div><div>A superconducting nanowire single-photon detector (SNSPD) is an optoelectrical device that works on the concept of hotspot formation and can detect a single photon. The associated readout circuit plays a vital role in determining the response of SNSPD. The available resources, complexity, and costs are major limiting factors in the actual readout circuit design. The preliminary information about the extrinsic effects that alter the SNSPD output from its desired value helps fabricate readout circuits. Here, the electrical equivalent circuit (EEC) for SNSPD has been simulated using LT spice software, and accordingly, a model has been developed to understand the readout circuit requirements. The EEC has been tested at room temperature by varying parameters like pulse width, bias voltage, capacitance and inductance. In addition, we have also designed and simulated a circuit for the multi-pixel photon counting scheme using a frequency multiplexing technique. Utilising this scheme, we observed that each EEC could be distinguished by its unique resonance frequency, reducing circuit complexity and power consumption. The results obtained indicate that their unique resonance frequency can identify triggered EEC.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"632 ","pages":"Article 1354689"},"PeriodicalIF":1.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579416","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 influence of the additional coil and ferromagnetic rings on high-temperature superconducting engine magnets","authors":"Wei Liu ,&nbsp;Wentao Zhang ,&nbsp;Weiwei Zhang ,&nbsp;Yongbin Wang ,&nbsp;Haowei Wu ,&nbsp;Donghui Liu","doi":"10.1016/j.physc.2025.1354665","DOIUrl":"10.1016/j.physc.2025.1354665","url":null,"abstract":"<div><div>A plasma engine with high-temperature superconducting (HTS) tapes offers advantages such as high efficiency, high thrust, and high specific impulse. However, due to the magnetic field-dependent characteristics of HTS tapes, the magnetic field at the coil ends tends to decrease rapidly. To mitigate this issue, a small additional coil can be wound at the coil end to enhance the magnetic field, or ferromagnetic rings can be employed to modify the local magnetic flux lines direction within the superconductor, thereby reducing the impact of radial magnetic fields on the critical current of the HTS tapes. In this study, to analyze the effects of the additional coil and ferromagnetic rings, a two-dimensional axisymmetric numerical model is established, and the T-A formulation is utilized to investigate the axial centerline magnetic field distribution of the HTS engine magnet. The simulation results indicate that varying the coil current primarily affects the peak value of the magnetic field without altering its configuration. The addition of an additional coil at the coil end effectively mitigates the rapid decline in the magnetic field at the coil end. The results also indicate that adding ferromagnetic rings can reduce the influence of the radial magnetic field on the critical current, thus enhancing the magnetic field at the coil ends. Furthermore, the results of the radial magnetic field distribution at the end of Coil-4 indicate that ferromagnetic rings can significantly reduce the magnitude of the radial magnetic field at the coil surface.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354665"},"PeriodicalIF":1.3,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445637","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":"Tilted solenoids magnet using superconducting stacked tapes","authors":"Junjie Du ,&nbsp;Zhilue Zeng ,&nbsp;Guoshu Zhang ,&nbsp;Kaijun Zhao ,&nbsp;Teng Liu ,&nbsp;Yujie Zhao ,&nbsp;Qi Wu ,&nbsp;Tuxing Zhan","doi":"10.1016/j.physc.2025.1354667","DOIUrl":"10.1016/j.physc.2025.1354667","url":null,"abstract":"<div><div>As a recently developed type of dipole field magnets, the tilted solenoids technology has great potential in various fields such as proton therapy, particle accelerators, and high-field applications. High-temperature superconducting materials can further enhance the magnetic field strength, reduce the bending radius, and lower the device cost. This research is based on differential geometry theory and proposes design methodology along with optimization principle for tilted solenoids magnet utilizing stacked high-temperature superconducting tapes. The engineering implementation strategies for tilted solenoid technology employing superconducting tapes are explored. Both single-turn and multi-turn coils are designed and fabricated respectively, and the critical currents are tested. Additionally, a double-layer tilted solenoids magnet was modeled; magnetic field simulation as well as higher-order analyses were conducted to validate the effectiveness of this methodology.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354667"},"PeriodicalIF":1.3,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445638","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":"Comparison of critical current and AC loss of 15 MVA superconducting machines with different topologies","authors":"Chao Luo,&nbsp;Jiabo Shou,&nbsp;Jien Ma,&nbsp;Youtong Fang","doi":"10.1016/j.physc.2025.1354664","DOIUrl":"10.1016/j.physc.2025.1354664","url":null,"abstract":"<div><div>Superconducting motors, characterized by their high current-carrying capacity, facilitate the exploration of varied topological designs beyond those possible with traditional motors. Nevertheless, many studies fail to account for the anisotropic properties of superconducting coils, resulting in inaccurate analyses of critical currents and AC losses. This paper introduces a simulation model for 15 MVA superconducting motors employing the H-formulation, which methodically assesses how the configurations of stator and rotor cores impact motor performance. The magnetic behavior of the rotor core, defined through the <span><math><mi>B</mi></math></span>-<span><math><mi>H</mi></math></span> curve derived via the ring sample method, is integrated into the model, enhancing its accuracy. The results reveal that incorporating rotor back core not only reduces the use of superconducting tape but also bolsters the magnetic field adjacent to the coil, thus improving its current-carrying capacity. This approach maximizes output capacity with minimal variations in excitation current. In contrast, including magnetic teeth in the stator curtails superconducting tape consumption and AC losses, it introduces space harmonics that elevate cogging torque. The study determines that the optimal topology combines stator and rotor back core while excluding magnetic teeth in both windings. Finally, a prototype of real-scale racetrack a high-temperature superconducting winding is manufactured, and the critical current within the different core structures is measured to validate its performance.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354664"},"PeriodicalIF":1.3,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445636","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":"Three-medium treatment of heat transfer in porous media and its application in CICC","authors":"Fengyang Han ,&nbsp;Zhifan Liu ,&nbsp;Zhifeng Liu ,&nbsp;Qiyong Zhang ,&nbsp;Xiaohong Wang ,&nbsp;Min Wang","doi":"10.1016/j.physc.2025.1354650","DOIUrl":"10.1016/j.physc.2025.1354650","url":null,"abstract":"<div><div>In this article, we derive the multi-temperature macroscopic model suitable for the porous CICC structure by using the volume average method. A CICC porous structure usually consists of three phases: one moving fluid phase (typically liquid helium) and two solid phases (typically copper and superconducting alloy). With the assumption of the equal average temperatures of the two solid phases, we obtain a two-temperature macroscopic model. The relevant closure problems are derived and solved numerically for a JT-60SA CICC structure and a ITER-TFPS CICC structure to obtain the macroscopic parameters. The calculated internal heat transfer coefficients are consistent with the experiment results, indicating the accuracy of the proposed two-temperature model. From the proposed two-temperature model, the temperature difference between the fluid and solid phases can be evaluated under a given heat source, which helps to determine whether the one-temperature model can be applied, or the two-temperature model needs to be applied. Typically, the one-temperature model may be suitable for CICC under nominal operation conditions, and the multi-temperature model is necessary during quenching process.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354650"},"PeriodicalIF":1.3,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445634","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 high-efficiency and compact insulation structures for high-temperature superconducting cables","authors":"Ting Jiao ,&nbsp;Honglei Li ,&nbsp;Jingwei Yu ,&nbsp;Yijia Huang","doi":"10.1016/j.physc.2025.1354653","DOIUrl":"10.1016/j.physc.2025.1354653","url":null,"abstract":"<div><div>This paper examines the optimization of insulation structures in high-temperature superconducting cables and experimentally assesses the impact of various low thermal conductivity spacer strips as support structures under different configurations of adiabatic layers. The study demonstrates significant reductions in thermal conduction, thereby enhancing insulation performance. These findings are valuable for guiding the miniaturized design of superconducting cables, facilitating more efficient power transmission.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354653"},"PeriodicalIF":1.3,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445635","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 and implementation of dummy fill for chemical-mechanical polishing in superconducting single flux quantum circuit fabrication process","authors":"Mingfan Chen ,&nbsp;Liliang Ying ,&nbsp;Lijuan Li ,&nbsp;Xue Zhang ,&nbsp;Yu Wu ,&nbsp;Weifeng Shi ,&nbsp;Hui Xie ,&nbsp;Linxian Ma ,&nbsp;Jie Ren","doi":"10.1016/j.physc.2025.1354668","DOIUrl":"10.1016/j.physc.2025.1354668","url":null,"abstract":"<div><div>We present the development of a planarized fabrication process for large-scale Single Flux Quantum (RSFQ) circuits, termed “SIMIT Nb03b.” This process utilizes chemical-mechanical polishing (CMP) to planarize the SiO₂ interlayer dielectric, enabling reduced feature sizes and improved scalability. Dummy fill has proven to be an effective technique for reducing process variation and to improve planarization for chemical mechanical polishing, however, few studies have been reported on how to determine the appropriate fill pattern for superconducting integrated process. In this work, dummy fill structures were strategically placed outside the circuit region to minimize their impact on the circuit's logical functionality. Then we determine the pattern density of dummy fill based on the standard cell library of the process and a fill pattern density of 45 %, length of 7 μm, and spacing of 3.5 μm between each other is chosen. Experimental results show that, at this dummy fill setup, the non-uniformity of the SiO₂ film thickness after CMP is &lt;5 %. We also developed an indirect method for assessing the residual SiO₂ thickness in circuit regions after CMP, which overcomes the limitations of direct measurement on small, narrow circuit patterns. This method enhanced the accuracy of measuring the residual SiO₂ film thickness in circuit regions by over 50 % compared to direct measurement techniques. The SIMIT Nb03b process has achieved a critical current of 6 kA/cm² and supported junction sizes down to 0.4 μm, small-scale superconducting integrated circuits fabricated by this process demonstrated a sufficiently wide operating margin, validating the efficacy of the developed fabrication technology.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354668"},"PeriodicalIF":1.3,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350398","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":"Analysis of “Revaluation of the lower critical field in superconducting H3S and LaH10 (Nature Comm. 13, 3194, 2022)” by V. S. Minkov et al","authors":"J.E. Hirsch ,&nbsp;M. van Kampen","doi":"10.1016/j.physc.2025.1354666","DOIUrl":"10.1016/j.physc.2025.1354666","url":null,"abstract":"<div><div>In <span><span>Nat Comm. 13, 3194, 2022</span><svg><path></path></svg></span> <span><span>[1]</span></span> and an “<span><span>Author Correction</span><svg><path></path></svg></span>” to it <span><span>[2]</span></span>, Minkov et al. presented magnetization data versus applied magnetic field for <span><math><mrow><msub><mrow><mi>H</mi></mrow><mrow><mn>3</mn></mrow></msub><mi>S</mi></mrow></math></span> and <span><math><mrow><mi>L</mi><mi>a</mi><msub><mrow><mi>H</mi></mrow><mrow><mn>10</mn></mrow></msub></mrow></math></span> under pressure, argued that the data provide evidence that these materials are superconducting at high temperatures, and extracted from the reported data the behavior of lower critical fields versus temperature. In several papers <span><span>[3]</span></span>, <span><span>[4]</span></span>, <span><span>[5]</span></span>, <span><span>[6]</span></span> analyzing Refs. <span><span>[1]</span></span>, <span><span>[2]</span></span> it was shown that the published magnetization data could not have been obtained from the reported measured data through the processes described in Refs. <span><span>[1]</span></span>, <span><span>[2]</span></span>. Recently, Minkov et al performed a revaluation of their experimental results <span><span>[7]</span></span> and argued that the results derived from their new analysis are consistent with the results reported earlier <span><span>[1]</span></span>. In addition, they made public the underlying data <span><span>[8]</span></span> from which the data published in Ref. <span><span>[1]</span></span> were derived. In this paper we analyze those underlying data and conclude that (a) the data published in Ref. <span><span>[1]</span></span> are incompatible with the underlying measured data, and (b) the revaluation analysis presented in Ref. <span><span>[7]</span></span> does not support the conclusions drawn by the authors in Ref. <span><span>[7]</span></span> nor Ref. <span><span>[1]</span></span>.</div></div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"630 ","pages":"Article 1354666"},"PeriodicalIF":1.3,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395170","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}