Physica C-superconductivity and Its Applications最新文献_第10页

On the path to superconductor broadband receivers 通往超导体宽带接收器之路

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-02-13 DOI: 10.1016/j.physc.2024.1354467

Nikolay V. Kolotinskiy, Victor K. Kornev

引用次数: 0

Electromagnetic design of MRI superconducting magnet based on novel hybrid optimization methods 基于新型混合优化方法的磁共振成像超导磁体电磁设计

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-02-02 DOI: 10.1016/j.physc.2023.1354425

Yunhao Mei , Qingyun Liu , Huiyu Du , Yufu Zhou , Zhengrong Liu , Lei Mo , Bensheng Qiu , Qing Zhang

{"title":"Electromagnetic design of MRI superconducting magnet based on novel hybrid optimization methods","authors":"Yunhao Mei , Qingyun Liu , Huiyu Du , Yufu Zhou , Zhengrong Liu , Lei Mo , Bensheng Qiu , Qing Zhang","doi":"10.1016/j.physc.2023.1354425","DOIUrl":"https://doi.org/10.1016/j.physc.2023.1354425","url":null,"abstract":"<div>This paper proposes a novel hybrid optimization algorithm that combines linear programming (LP), genetic algorithm (GA), and nonlinear programming (NLP) to achieve the optimal design of highly homogeneous superconducting magnets for MRI systems. Initially, the predetermined rectangular region is divided into an array of superconductor coils. Then, linear programming is utilized to minimize the consumption of superconducting conductors as the objective function and to obtain the nonzero current regions by considering the field peak-to-peak uniformity in the diameter of the spherical volume (DSV) and the range of the 5 Gauss stray field as constraints. Subsequently, the genetic algorithm is employed to convert the nonzero current regions into coils with rectangular cross-sections. Finally, the NLP is applied to adjust the position of each coil to obtain the magnet criteria. An illustrative example is provided: an actively shielded MRI superconducting magnet with a center field strength of 1.5 T. The effectiveness of this optimization method is demonstrated through the design, electromagnetic analysis, and stress analysis conducted on this example.</div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"617 ","pages":"Article 1354425"},"PeriodicalIF":1.7,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139674924","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}

引用次数: 0

Model of a superconducting spin valve with insulating layers 带绝缘层的超导自旋阀模型

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-01-29 DOI: 10.1016/j.physc.2024.1354461

A.A. Kamashev, A.A. Validov, N.N. Garif'yanov, I.A. Garifullin

引用次数: 0

Vortex state in a 3D superconducting mesoscopic wedge 三维超导介观楔中的涡旋态

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-01-26 DOI: 10.1016/j.physc.2024.1354450

C.A. Aguirre , P. Díaz , D. Laroze , A.S. Mosquera Polo , J. Barba-Ortega

引用次数: 0

Periodic-threshold amalgamated quasi-one-junction SQUID comparator 周期阈值汞齐化准单结 SQUID 比较器

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-01-19 DOI: 10.1016/j.physc.2024.1354445

Siqi Li , Minghui Niu , Huanli Liu , Xiaoping Gao , Liliang Ying , Jie Ren

{"title":"Periodic-threshold amalgamated quasi-one-junction SQUID comparator","authors":"Siqi Li , Minghui Niu , Huanli Liu , Xiaoping Gao , Liliang Ying , Jie Ren","doi":"10.1016/j.physc.2024.1354445","DOIUrl":"10.1016/j.physc.2024.1354445","url":null,"abstract":"<div>This article proposes a periodic-threshold superconductive comparator named amalgamated quasi-one-junction SQUID comparator (AQOS) for sensitivity enhancement. The comparator employs a pair of compound Josephson-junction SQUID with magnetically-controlled effective critical current in quantization to relieve the constraints on the period current without disrupting the non-hysteresis operation state. As a result, the AQOS comparator can achieve three times more comparing operations than the quasi-one-junction SQUID (QOS) comparators, corresponding to a 9 dB sensitivity improvement. The AQOS comparator also adopts the complementary structure and feedback-free topology for linearity and robustness. It can reach a 30 GS/s sampling rate, 0.5 mA period current, −25 dBm sensitivity, more than ±10 % bias current margin, deviation of quantization current peak-to-peak magnitude that is about 10 % of the mean, and the 4.4 dB average DC duty bias margin in simulation from 1 GHz to 30 GHz with a process of 6 kA/cm2 Josephson critical current density. A 2-bit AQOS comparator has been fabricated with the SIMIT Nb03 process for the qualification test. It has passed functional tests at low frequency, and its performance metrics, including period current, sensitivity, and bias current margin, have also been proven.</div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"618 ","pages":"Article 1354445"},"PeriodicalIF":1.7,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139509632","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}

引用次数: 0

First-principles study on the electronic structure and optical properties of orthorhombic CaTiO3 under different pressures 不同压力下正交钙钛矿的电子结构和光学特性的第一性原理研究

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-01-17 DOI: 10.1016/j.physc.2024.1354447

Xinping Guo , Yongbo Li , Wenbo Xiao , Huaming Wu

{"title":"First-principles study on the electronic structure and optical properties of orthorhombic CaTiO3 under different pressures","authors":"Xinping Guo , Yongbo Li , Wenbo Xiao , Huaming Wu","doi":"10.1016/j.physc.2024.1354447","DOIUrl":"https://doi.org/10.1016/j.physc.2024.1354447","url":null,"abstract":"<div>The lattice constants, band structure, density of states (DOS), and optical properties of orthorhombic CaTiO3 in the pressure range of 0–100 GPa were calculated using the GGA-PBE method based on first-principles in this study. Geometry structure optimization results show that with an increase in pressure, the lattice constants of orthorhombic CaTiO3 decrease and the band gap (Eg) value increases. However, increasing pressure does not change the type of band gap in orthorhombic CaTiO3, which remains a direct band gap with the valence band maximum (VBM) and conduction band minimum (CBM) both located at the G point. The calculated electronic structure results indicate a gradual decrease in the DOS peak intensity for Ca–p, Ca–d, O–s, and O–p orbitals with increasing pressure, while the DOS peak intensity for the Ti atom remains relatively stable. Meanwhile, the valence band near the Fermi level shifts to the lower energies, while the conduction band shifts to the higher energies. Further calculations show that the optical properties exhibit a consistent blue shift as pressure increases. The research findings reveal that orthorhombic CaTiO3 demonstrates low absorption of visible light and high absorption of ultraviolet (UV) light. Moreover, as the pressure increases, the absorption of visible light further diminishes, while the absorption of UV light gradually intensifies. The findings presented in this paper offer significant insights for investigating the electronic structure and optical properties of orthorhombic CaTiO3 under varying pressure conditions.</div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"617 ","pages":"Article 1354447"},"PeriodicalIF":1.7,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139487825","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}

引用次数: 0

Hysteresis loops in measurements of the magnetic moment of hydrides under high pressure: Implications for superconductivity 高压下氢化物磁矩测量中的磁滞环：对超导性的影响

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-01-14 DOI: 10.1016/j.physc.2024.1354449

J.E. Hirsch

{"title":"Hysteresis loops in measurements of the magnetic moment of hydrides under high pressure: Implications for superconductivity","authors":"J.E. Hirsch","doi":"10.1016/j.physc.2024.1354449","DOIUrl":"10.1016/j.physc.2024.1354449","url":null,"abstract":"<div>Measurements of magnetic moments of hydride materials under high pressure have been claimed to prove the existence of superconductivity in these materials (Drozdov et al., 2015; Minkov et al., 2021; Minkov et al., 2022; Minkov et al., 2023; Eremets et al., 2022) . However, detection of the signal from the small sample requires subtraction of a large background contribution whose details are largely unknown. Here we analyze reported measurements and point out that the resulting hysteresis loops are incompatible with the conclusion that they result from superconductivity, independent of what assumptions are made about the background signal. We argue that this also invalidates the conclusion that the magnetic moment measured after the external magnetic field is turned off is evidence for trapped magnetic flux resulting from superconducting currents, as proposed in Minkov et al. (2023). Our results imply that to date no magnetic evidence for the existence of high temperature superconductivity in hydrides under pressure exists, despite multiple claims to the contrary.</div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"617 ","pages":"Article 1354449"},"PeriodicalIF":1.7,"publicationDate":"2024-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0921453424000145/pdfft?md5=501b29fb90757998855b0f5deef313e2&pid=1-s2.0-S0921453424000145-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139470198","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}

引用次数: 0

The local rupture of the superconductivity and the curvature of the mesoscopic sample 超导的局部断裂和介观样品的曲率

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2024-01-13 DOI: 10.1016/j.physc.2024.1354436

Isaías G. de Oliveira, Jonathan S. de Morais, Paloma F. Ferreira

{"title":"The local rupture of the superconductivity and the curvature of the mesoscopic sample","authors":"Isaías G. de Oliveira, Jonathan S. de Morais, Paloma F. Ferreira","doi":"10.1016/j.physc.2024.1354436","DOIUrl":"https://doi.org/10.1016/j.physc.2024.1354436","url":null,"abstract":"<div>In this article we revisit a well-known effect in superconductors, which is the penetration of the magnetic field by regions of greater radius of curvature (Tinkham, 2008; De Gennes, 1966). This is exposed in the literature but without a quantitative solution. Here we solve this problem by two distinct numerical simulations. We calculate the superconducting current density using numerical simulations via the London theory in the Meissner state and numerical simulations using the time-dependent Ginzburg–Landau (TDGL) theory for the vortex state. In both simulations, the results obtained are in agreement, as could not be otherwise. We show that in the Meissner state the current density increases much faster in the region where the radius of curvature is larger, thus reaching the critical value first in this location, and therefore local breakdown of superconductivity occurs. In the vortex state, our simulations, using TDGL, show that the vortices penetrate through exactly the same location pointed out by the previous simulation. For this study we worked with a superconducting needle with an ellipsoidal mesoscopic cross section.</div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"617 ","pages":"Article 1354436"},"PeriodicalIF":1.7,"publicationDate":"2024-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139434484","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}

引用次数: 0

Fabrication and characterization of sub-micron high current density NbN Josephson junctions for large-scale digital circuits 用于大规模数字电路的亚微米级高电流密度氮化铌约瑟夫森结的制作与特性分析

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2023-12-27 DOI: 10.1016/j.physc.2023.1354434

Yingyi Shao , Huiwu Wang , Wei Peng , Jie Ren , Zhen Wang

{"title":"Fabrication and characterization of sub-micron high current density NbN Josephson junctions for large-scale digital circuits","authors":"Yingyi Shao , Huiwu Wang , Wei Peng , Jie Ren , Zhen Wang","doi":"10.1016/j.physc.2023.1354434","DOIUrl":"10.1016/j.physc.2023.1354434","url":null,"abstract":"<div>We have developed a fabrication process based on Chemical Mechanical Polishing (CMP) for the sub-micron NbN Josephson junctions on single-crystal MgO substrates. The NbN junctions were fabricated with epitaxial NbN/AlN/NbN trilayers deposited by reactive DC magnetron sputtering. The top electrode of the junction was exposed using CMP to contact the NbN wire without opening the submicron via through the dielectric. It has produced submicron NbN junctions with areas as small as 0.09 μm2. We have fabricated NbN tunnel junctions with a wide range of critical current density Jc. The NbN junctions show excellent Josephson tunneling characteristics, the gap voltage Vg is 5.8 mV and the quality factor Rsg/Rn is 12 for the junctions with a Jc of 10.7 kA/cm2, and Vg is 5.3 mV and Rsg/Rn is 4 for the junctions with a Jc of 150.5 kA/cm2. The 1000-junction arrays were fabricated and their I-V characteristics were measured, critical current uniformity was obtained and the standard deviation is about 5%. The high Jc sub-micron NbN junctions will be helpful in developing large-scale NbN SFQ circuits with high operating frequency.</div>","PeriodicalId":20159,"journal":{"name":"Physica C-superconductivity and Its Applications","volume":"616 ","pages":"Article 1354434"},"PeriodicalIF":1.7,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139056896","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}

引用次数: 0

Modeling of induced currents in a type-II superconducting cylinder of finite length in a transverse magnetic field 有限长度的 II 型超导圆柱体在横向磁场中的感应电流建模

IF 1.7 3区物理与天体物理

Physica C-superconductivity and Its Applications Pub Date : 2023-12-27 DOI: 10.1016/j.physc.2023.1354423

Yuriy Zhilichev

引用次数: 0