Superconductor Science and Technology最新文献

{"title":"Thermal degradation analysis and optimization of controlled heat treatment for stacked high temperature superconducting tapes","authors":"Shige Yang, Bohan Tang, Zhilai Yue, Hui Yu, Bowen Xie, Sicheng Li, Yanquan Chen, Rui Niu, Jun Zhao, Peng Zhou, Wenge Chen, Shili Jiang, Donghui Jiang, Guangli Kuang","doi":"10.1088/1361-6668/ad6ada","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6ada","url":null,"abstract":"High temperature superconducting (HTS) tapes have crucial applications for generating high magnetic fields with minimal power input. Given a single tape has a limited current-carrying capacity, stacked tapes are common, fabricated through methods like solder soldering or epoxy impregnation requiring heat treatment. In this work, we have investigated the efficient region for vacuum heat treatment applicable of commercial HTS tapes, analysed the thermal degradation principles and accordingly proposed a controlled heat treatment process for stacked HTS tapes to achieve more precise regulation of the critical current (<inline-formula>\u0000<tex-math><?CDATA ${I_{text{c}}}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:msub><mml:mi>I</mml:mi><mml:mrow><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6adaieqn1.gif\"></inline-graphic></inline-formula>). This heat treatment process was explored using a specialized multi-temperature zone vacuum system. Critical parameters in this process include heat treatment temperature, duration and pressure on the tape. A series of experiments were conducted at 77 K in a self-field to investigate how these parameters affect the superconductivity performance of stacked HTS tapes. Based on the experimental results, an optimal heat treatment process has been proposed. Under the current process, with the heat treatment temperature set at 200 °C, duration at 20 min, and pressure on the tape at 12 MPa, the samples exhibit favourable properties characterized by a smooth and neat appearance without defects such as pinholes or false soldering, and the superconductivity performance can be consistently maintained at more than 97%. The obtained measurements were compared with simulated results, demonstrating an error margin within 0.5%. Moreover, precise control of <inline-formula>\u0000<tex-math><?CDATA ${I_{text{c}}}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:msub><mml:mi>I</mml:mi><mml:mrow><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math><inline-graphic xlink:href=\"sustad6adaieqn2.gif\"></inline-graphic></inline-formula> is achieved, tailored to tape and stacking specifications, allowing manageable degradation as required. This heat treatment process for stacked HTS tapes holds significant importance, especially in the context of designing cable-in-conduit conductors fabricated with stacked HTS tapes. It serves as a valuable reference for further advancements in this field.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast current discharging using self-coupling energy absorption for insulated high temperature superconductor magnets","authors":"Jingyi Liu, Zhen Lu, Yawei Wang, Qingqing Yang, Yutong Fu, Yue Zhao, Zhijian Jin","doi":"10.1088/1361-6668/ad6e26","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6e26","url":null,"abstract":"Quench protection has always been challenging for high-temperature superconductor (HTS) coils. Fast current discharge after quench detection is important for a successful coil protection. The copper plates initially intended for cooling can significantly accelerate the discharging process for HTS coils through electromagnetic coupling between coils and copper plates. However, the underlying physical mechanism of this technique has not been studied thoroughly. Here we present a detailed study on the electromagnetic and thermal characteristics of HTS coils coupled with copper plates through experiments and simulations. The results show that a considerable current rebound occurs after an accelerating current drop in the early stage of the fast-discharging process. This coil current rebound is induced by temperature rise as well as the resistivity of copper plates, which are heated by induced eddy current. The heat transfer from copper plates can uniformly heat the whole coil rapidly, which speeds up the discharging process, meanwhile it can also induce overcurrent quench risk. A 30 T@20 K HTS magnet with 36 single pancakes is analyzed. The coupling copper plates can make the coil current drop to 36.9% within the initial 8 ms. The temperature rise induced by copper plates shows a considerable nonuniform distribution among the multiple coil systems. The protection can be enhanced by optimizing the resistivity of copper plates and magnetic coupling strength between plates and coils. This technique has great potential for the protection of insulated HTS magnets.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Suppression of grain boundary weak link by Ca doping in YBa2Cu3O7 coated conductor","authors":"Kentaro Yamamoto, Yutaka Yoshida, Tomoya Horide","doi":"10.1088/1361-6668/ad68d7","DOIUrl":"https://doi.org/10.1088/1361-6668/ad68d7","url":null,"abstract":"YBa₂Cu₃O₇ coated conductors are a strategic material for superconducting applications such as high field magnets, fusion, and motors. Grain boundaries reduce the critical current density (<italic toggle=\"yes\">J</italic>_c) even at a tilt angle as low as 5°, but the successful development of the highly oriented substrates seemed to overcome the weak link problem at grain boundaries. However, it reappears when we visit the homogeneity of the coated conductors. To suppress the weak link in the coated conductors, the Ca doping was investigated. The Ca-doped YBa₂Cu₃O₇ films were fabricated on the moderately oriented substrates. While the grain boundaries in the moderately oriented substrates significantly degraded the <italic toggle=\"yes\">J</italic>_c without Ca doping, the Ca doping improved the <italic toggle=\"yes\">J</italic>_c especially at low temperature. This indicates that the tilt angle dependence of <italic toggle=\"yes\">J</italic>_c was varied by the Ca doping. While the <italic toggle=\"yes\">J</italic>_c for the moderately oriented substrate was 20 times smaller than that for the highly oriented substrate, the Ca doping restored 1/2 of the <italic toggle=\"yes\">J</italic>_c for the highly oriented substrate at 40 K and 9 T. The vortex structure changed from Abrikosov Josephson vortices to the Abrikosov vortices with increasing the Ca content. The combination of Ca doping and moderate substrate texture is another design of coated conductors. The Ca doping can patch the local degradation of the substrate texture to mass produce the practical coated conductors with improved homogeneity.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"73 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast and accurate 3D FEM model for electromagnetic simulations of no-insulation HTS coils based on polygon-anisotropic-resistivity","authors":"Zhuoyan Zhong, Wei Wu, Zhijian Jin","doi":"10.1088/1361-6668/ad68d6","DOIUrl":"https://doi.org/10.1088/1361-6668/ad68d6","url":null,"abstract":"For no-insulation (NI) high-temperature superconducting (HTS) coils, a 3D electromagnetic model, which is fast and accurate, conducive to establish, and straightforward to multi-physics coupling, is still required. This paper introduces a polygon-anisotropic-resistivity (PAR) method for 3D FEM electromagnetic simulations of NI HTS coils. This model avoids dividing each tape into the specific HTS-tape layer and turn-to-turn contact layer, which yields: (1) a reduced computational burden; (2) improved convergence due to smaller element aspect ratios. The significance of the PAR method lies in its indispensable role in achieving a 3D anisotropic-resistivity model with high computing speed and accuracy. The proposed PAR model is rigorously evaluated through three types of simulations: (1) charge and discharge tests; (2) AC losses of the NI coil subjected to AC fields with a DC current supply; (3) heat-triggered quench and recovery scenarios. For these simulations, the PAR model is validated by comparisons with the full-element model, namely, the 3D FEM model that explicitly incorporates each specific HTS-tape layer and turn-to-turn contact layer in the <italic toggle=\"yes\">H</italic>-formulation model, and is also validated by previous experimental data for AC losses. Good consistency is observed. The computing speed of the PAR model is tested to be 12–38 times that of the full-element model with the same accuracy. The PAR model achieves a 40% reduction in degrees of freedom compared to the full-element model, with the same mesh density along the HTS tape width and length, facilitating more precise and larger scale coil simulations within the same computational memory limits. Additionally, the PAR model entirely eliminates the inherent inaccuracies found in the conventional-anisotropic-resistivity 3D model, which stem from discrepancies between the arranged anisotropic-resistivity and the actual computed coil meshes. The proposed PAR model will enhance the prevalence of 3D electromagnetic analyses of NI HTS coils.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The A-15-type superconducting hydride La4H23: a nanograined structure with low strain, strong electron-phonon interaction, and a moderate level of nonadiabaticity","authors":"Evgeny F Talantsev, Vasiliy V Chistyakov","doi":"10.1088/1361-6668/ad637e","DOIUrl":"https://doi.org/10.1088/1361-6668/ad637e","url":null,"abstract":"For seven decades, when referring to A-15 superconductors, we meant metallic A&lt;sub&gt;3&lt;/sub&gt;B alloys (where A is a transition metal, and B is group IIIB and IVB elements) discovered by Hardy and Hulm (1953 &lt;italic toggle=\"yes\"&gt;Phys. Rev.&lt;/italic&gt; &lt;bold&gt;89&lt;/bold&gt; 884). Nb&lt;sub&gt;3&lt;/sub&gt;Ge exhibited the highest superconducting transition temperature, &lt;italic toggle=\"yes\"&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/italic&gt; = 23K, among these alloys. One of these alloys, Nb&lt;sub&gt;3&lt;/sub&gt;Sn, is the primary material in modern applied superconductivity. Recently, Guo &lt;italic toggle=\"yes\"&gt;et al&lt;/italic&gt; (2024 &lt;italic toggle=\"yes\"&gt;Natl Sci. Rev.&lt;/italic&gt; nwae149, &lt;ext-link ext-link-type=\"uri\" xlink:href=\"https://doi.org/10.1093/nsr/nwae149\"&gt;https://doi.org/10.1093/nsr/nwae149&lt;/ext-link&gt;) extended the family of superconductors where the metallic ions are arranged in the beta tungsten (A-15) sublattice by observation of &lt;italic toggle=\"yes\"&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/italic&gt;&lt;sub&gt;,zero&lt;/sub&gt; = 81K in the La&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;23&lt;/sub&gt; phase compressed at &lt;italic toggle=\"yes\"&gt;P&lt;/italic&gt; = 118 GPa. Despite the fact that La&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;23&lt;/sub&gt; has much lower &lt;italic toggle=\"yes\"&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/italic&gt; in comparison with the near-room-temperature superconducting LaH&lt;sub&gt;10&lt;/sub&gt; phase (&lt;italic toggle=\"yes\"&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/italic&gt;&lt;sub&gt;,zero&lt;/sub&gt; = 250K at &lt;italic toggle=\"yes\"&gt;P&lt;/italic&gt; ∼ 200 GPa) discovered by Drozdov &lt;italic toggle=\"yes\"&gt;et al&lt;/italic&gt; (2019 &lt;italic toggle=\"yes\"&gt;Nature&lt;/italic&gt; &lt;bold&gt;569&lt;/bold&gt; 531), La&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;23&lt;/sub&gt; holds the record for the highest &lt;italic toggle=\"yes\"&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/italic&gt; within the A-15 family. Cross &lt;italic toggle=\"yes\"&gt;et al&lt;/italic&gt; (2024 &lt;italic toggle=\"yes\"&gt;Phys. Rev.&lt;/italic&gt; B &lt;bold&gt;109&lt;/bold&gt; L020503) confirmed the high-temperature superconductivity in compressed La&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;23&lt;/sub&gt;. In this paper, we analyzed available experimental data measured in La&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;23&lt;/sub&gt; and found that this superconductor exhibits a nanograined structure, 5.5 nm ⩽ &lt;italic toggle=\"yes\"&gt;D&lt;/italic&gt; ⩽ 35 nm, low crystalline strain, &lt;inline-formula&gt;\u0000&lt;tex-math&gt;&lt;?CDATA $left| {{varepsilon }} right|$?&gt;&lt;/tex-math&gt;&lt;mml:math overflow=\"scroll\"&gt;&lt;mml:mrow&gt;&lt;mml:mrow&gt;&lt;mml:mo&gt;|&lt;/mml:mo&gt;&lt;mml:mrow&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;ε&lt;/mml:mi&gt;&lt;/mml:mrow&gt;&lt;/mml:mrow&gt;&lt;mml:mo&gt;|&lt;/mml:mo&gt;&lt;/mml:mrow&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;inline-graphic xlink:href=\"sustad637eieqn1.gif\"&gt;&lt;/inline-graphic&gt;&lt;/inline-formula&gt; ⩽ 0.003, strong electron–phonon interaction, 1.5 ⩽ λ&lt;sub&gt;e-ph&lt;/sub&gt;⩽ 2.55, and a moderate level of nonadiabaticity, 0.18 ⩽ Θ&lt;italic toggle=\"yes\"&gt;&lt;sub&gt;D&lt;/sub&gt;&lt;/italic&gt;/&lt;italic toggle=\"yes\"&gt;T&lt;/italic&gt;&lt;sub&gt;F&lt;/sub&gt; ⩽ 0.22 (where Θ&lt;italic toggle=\"yes\"&gt;&lt;sub&gt;D&lt;/sub&gt;&lt;/italic&gt; is the Debye temperature, and &lt;italic toggle=\"yes\"&gt;T&lt;/italic&gt;&lt;sub&gt;F&lt;/sub&gt; is the Fermi temperature). We found that the derived Θ&lt;italic toggle=\"yes\"&gt;&lt;sub&gt;D&lt;/sub&gt;&lt;/italic&gt;/&lt;italic toggle=\"yes\"&gt;T&lt;/italic&gt;&lt;sub&gt;F&lt;/sub&gt; and &lt;italic toggle=\"yes\"&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/italic&gt;/&lt;italic toggle=\"yes\"&gt;T&lt;/italic&gt;&lt;sub&gt;F&lt;/sub&gt; values for the La&lt;sub&gt;","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of K excess in microstructure of (Ba0.6K0.4)Fe2As2 superconducting powders","authors":"Emilio Bellingeri, Cristina Bernini, Federico Loria, Andrea Traverso, Alessandro Leveratto, Valeria Braccini, Amalia Ballarino, Andrea Malagoli","doi":"10.1088/1361-6668/ad68d4","DOIUrl":"https://doi.org/10.1088/1361-6668/ad68d4","url":null,"abstract":"Iron-based superconductors (IBSs) are promising for high-field applications due to their exceptional characteristics, like ultrahigh upper critical field and minimal electromagnetic anisotropy. Creating multifilamentary superconducting wires with elevated transport critical current density is essential for practical use. The Powder in Tube (PIT) technique is commonly used for this purpose, but achieving optimal results requires careful exploration of powder microstructural properties. This is particularly crucial for superconductors like (Ba,K)122, the IBS most promising from an applicative point of view, where factors such as reactivity, volatility, and toxicity of constituent elements affect phase formation. Potassium volatility often leads to nonstoichiometric conditions, introducing excess potassium in the formulation. This study focuses on the impact of potassium excess <italic toggle=\"yes\">δ</italic> on the microstructural properties of the ‘optimally doped’ (Ba_0.6K_{0.4+<italic toggle=\"yes\">δ</italic>})Fe₂As₂ phase (0 ⩽ <italic toggle=\"yes\">δ</italic> ⩽ 0.08). Using techniques like Scanning Electron Microscopy, x-ray diffraction, and temperature-dependent magnetization measurements, we demonstrate the ability to produce nearly pure powders of the superconducting phase with controlled grain size. Our findings are relevant for PIT wire fabrication, where grain size strongly affects mechanical deformation. Grain size also influences transport properties, as observed in previous studies, where reducing grain size enhanced current-carrying capability at high magnetic fields.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the effect of rolling deformation on the electro-mechanical limits of Nb3Sn wires produced by RRP® and PIT technologies","authors":"T Bagni, C Calzolaio, G Bovone, J Ferradas-Troitino, C Barth, A Ballarino and C Senatore","doi":"10.1088/1361-6668/ad6a9c","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6a9c","url":null,"abstract":"Future high-field magnets for particle accelerators hinge on the crucial development of advanced Nb3Sn wires engineered to withstand the large stresses generated during magnet assembly and operation. The superconducting properties of Nb3Sn enable the design of compact accelerator-quality magnets above 10 T, but at the same time the brittleness and strain sensitivity of the material impose careful consideration of the mechanical limits. In addition, accelerator magnets are wound using Rutherford cables and the cabling process generates deformations in the wire that can affect its electro-mechanical performance. This paper reports on the impact of the rolling deformation on the transverse stress tolerance of high-performance restacked-rod-process (RRP®) and powder-in-tube (PIT) Nb3Sn wires. Rolling deformation was used to mimic the effect of cabling on the wire shape. Deformed samples were compared to reference round wires in term of stress dependence and irreversible limit (σirr) of the critical current (Ic) under transverse compressive loads up to 240 MPa. Experiments were performed at 4.2 K, 19 T, on resin-impregnated single wires that imitate the operating conditions in a Rutherford cable of an accelerator magnet. The results show that rolling deformation has a detrimental effect on the initial Ic of PIT wires, but it does not influence the behavior of the wire under stresses above 70 MPa. On the other hand, the deformation of RRP® wires leads to an improved σirr without affecting the initial Ic. Additionally, a 2D-mechanical finite element method model of the RRP® wire was developed to investigate the impact of the wire geometry on the plastic deformation of the copper matrix, which induces residual stresses on Nb3Sn and is the main cause for the permanent reduction of Ic. Based on the model results, an alternative layout of the wire was proposed that improves its stress tolerance without affecting its electrical transport properties.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"99 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elastic-plastic conductor damage evaluation at over 0.4% strain using a high-stress REBCO coil","authors":"Jeseok Bang, Griffin Bradford, Kwangmin Kim, Jonathan Lee, Anatolii Polyanskii and David Larbalestier","doi":"10.1088/1361-6668/ad6a9d","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6a9d","url":null,"abstract":"Recent reports on screening current stress simulations of high-field REBCO magnets frequently present peak stresses over 1 GPa. However, this result is probably an unrealistic artifact of purely elastic calculations, considering the macroscopic yield and fracture stresses of approximately 900 MPa and less than 1.1 GPa for Hastelloy substrate-coated conductors. Here, we evaluate elastic-plastic conductor damage at over 0.4% strain using a high-stress REBCO coil exposed to a high field to explore this elastic-plastic regime. The coil was located off-center in a low-temperature superconductor magnet so as to induce a significant screening current in the enhanced radial field. Voltage taps, a Hall sensor, and two strain gauges were used for the instrumentation. We obtained strains exceeding 0.4% near the outward edge during the coil current charge from 350 A to 390 A, where the coil was exposed to external axial and radial magnetic fields of 13 T and 0.5 T. Post mortem results showed wavy plastic deformation, electrical damage, and REBCO defects. An elastic-plastic simulation reproduced the measured strains and predicted that ∼1 GPa stress is sufficient to induce ∼0.9% strain, thus validating our initial concerns with purely elastic models. This paper provides our experimental and simulation results.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of nitrogen content on the structure and superconductivity of reactive sputtered NbTiN thin films","authors":"L Zhang, Y L Zhong, J J Xie, H Jin, W B Zhao, W Peng, L Chen and Z Wang","doi":"10.1088/1361-6668/ad6adc","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6adc","url":null,"abstract":"In this research, we have studied the structural and electrical properties of NbTiN films deposited on MgO and SiO2/Si substrates by reactive dc sputtering. The formation of stoichiometric NbTiN is very sensitive to N concentration and can be easily adjusted by changing the discharge current and Ar: N2 ratio along the current–voltage curves (IVCs) of the NbTi target. Excessive or insufficient N concentration in NbTiN leads to sublattice expansion or distortion, resulting in a decrease in critical temperature Tc. At Ar: N2 ratio of 30:4 and discharge current of 2.2 A, Tc as high as 15.8 K and 15.3 K has been obtained for 200 nm thick NbTiN/MgO and NbTiN/SiO2/Si samples, respectively. In addition, the critical density Jc of the 4 μm-wide and 7 nm-thick NbTiN film grown on MgO substrate at 2 K reaches 19.2 MA cm−2, which is approximately twice as high as the 10.9 MA cm−2 of the same-sized NbTiN film grown on SiO2/Si substrate. Therefore, by further fine-tuning the N concentration in combination with the IVCs of the target, high-quality stoichiometric NbTiN can be obtained.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SuperSIM: A comprehensive benchmarking framework for neural networks using superconductor josephson devices","authors":"Guangxian Zhu, Yirong Kan, Renyuan Zhang, Yasuhiko Nakashima, Wenhui Luo, N. Takeuchi, Nobuyuki Yoshikawa, O. Chen","doi":"10.1088/1361-6668/ad6d9e","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6d9e","url":null,"abstract":"\u0000 This paper introduces SuperSIM, a benchmarking framework tailored for neural networks using superconducting Josephson devices, specifically focusing on Adiabatic Quantum Flux Parametron (AQFP) based Processing-in-Memory (PIM) architectures. Our framework offers in-depth architecture-level simulations and performance assessments to enhance AQFP PIM chip development. It supports single and multi-bit PIM designs, various AQFP memory cell types, and diverse clocking methods. Additionally, it integrates circuit-level models for precise energy, delay, and area measurements, ensuring accurate performance evaluation. The framework includes application, device, and architectural layers for versatile configurations and cycle-accurate energy, latency, and area simulations. Experiments validate our framework, with case studies on algorithm and architecture-level features, examining data precision, crossbar size, operating frequency and clocking scheme impacts on computational accuracy, energy use, overall latency and hardware cost.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"16 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}