Pub Date : 2025-12-01DOI: 10.1088/1361-6668/ae2840
YanLan Cui, Wan‐Min Yang
Abstract In this work, the effect of Y content on Gd 2− r Y r Ba 4 CuNbO y ( r = 0, 0.6, 1, 1.4, 2, Gd 2− r Y r -411) nano-powders was thoroughly explored for the first time. The results demonstrate that Y doping can effectively modulate the particle size of Gd 2− r Y r -411 nano-particles. The GdBCO bulks with solid phase compositions of [92 wt% (Gd 2 O 3 + 1.2BaCuO 2 ) + 7 wt% Gd 2− r Y r -411 + 1 wt% CeO 2 ] were prepared using the Gd + 011 top-seeded infiltration and growth method. The results indicated that both the levitation force ( F L ) and the trapped field ( B tr ) of the sample initially increased and then decreased with the Y content in the doped Gd 2− r Y r -411 nano-powders increased. The optimal values of F L (159 N at 77 K, 0.5 T) and B tr (0.92 T at 77 K, 1 T) of the sample were achieved by doping 7 wt% GdY-411 nano-powder, which were enhanced by 48 N and 0.22 T over the undoped sample. The calculated maximum levitation force density of the sample reached up to 19.8 N cm −2 . A B tr of 1.23 T has been recorded finally at 77 K for the GdBCO/CeO 2 contained GdY-411 with 32 mm diameter. The above results demonstrate that the interface defects generated by Gd 2− r Y r -411 nano-particles can serve as effective magnetic flux pinning centers, which enhances the performance of the samples. In addition, compared with the doping of the traditional RE2411, the F L and B tr increased by over 35% and 21%, respectively. Our work provides systematic reference for studying the influence of mixed rare earth type nano-powders on the performance of REBCO bulk superconductor.
本文首次深入研究了Y含量对Gd 2−r Y r Ba 4 CuNbO Y （r = 0,0.6, 1,1.4, 2, Gd 2−r Y r -411）纳米粉体的影响。结果表明，Y掺杂能有效调节Gd 2−r Y r -411纳米粒子的粒径。采用Gd + 011顶种浸渍生长法制备了固相组成为[92 wt% (gde2o3 + 1.2BaCuO 2) + 7 wt% gde2o3 - r Y r -411 + 1 wt% ceo2]的GdBCO块体。结果表明：随着Gd 2−r Y r -411纳米粉体中Y含量的增加，样品的悬浮力（F L）和捕获场（B tr）均呈现先增大后减小的趋势；通过添加7wt % GdY-411纳米粉体，得到了最佳的fl值（77 K， 0.5 T时159 N）和btr值（77 K， 1 T时0.92 T），比未掺杂的样品增强了48 N和0.22 T。计算得到试样的最大悬浮力密度可达19.8 N cm−2。对于含有GdY-411的直径为32 mm的GdBCO/CeO 2，在77 K时最终记录到1.23 T的A B tr。上述结果表明，Gd 2−r Y r -411纳米粒子产生的界面缺陷可以作为有效的磁通量钉钉中心，从而提高了样品的性能。此外，与传统的RE2411掺杂相比，fl和btr分别提高了35%和21%以上。本研究为研究混合稀土型纳米粉体对REBCO块体超导体性能的影响提供了系统的参考。
{"title":"Fabrication of high levitation force and trapped field single-domain GdBCO/CeO <sub>2</sub> bulk by doping Gd <sub> 2− <i>r</i> </sub> Y <i> <sub>r</sub> </i> -411 nano-particles using the Gd + 011 TSIG method","authors":"YanLan Cui, Wan‐Min Yang","doi":"10.1088/1361-6668/ae2840","DOIUrl":"https://doi.org/10.1088/1361-6668/ae2840","url":null,"abstract":"Abstract In this work, the effect of Y content on Gd 2− r Y r Ba 4 CuNbO y ( r = 0, 0.6, 1, 1.4, 2, Gd 2− r Y r -411) nano-powders was thoroughly explored for the first time. The results demonstrate that Y doping can effectively modulate the particle size of Gd 2− r Y r -411 nano-particles. The GdBCO bulks with solid phase compositions of [92 wt% (Gd 2 O 3 + 1.2BaCuO 2 ) + 7 wt% Gd 2− r Y r -411 + 1 wt% CeO 2 ] were prepared using the Gd + 011 top-seeded infiltration and growth method. The results indicated that both the levitation force ( F L ) and the trapped field ( B tr ) of the sample initially increased and then decreased with the Y content in the doped Gd 2− r Y r -411 nano-powders increased. The optimal values of F L (159 N at 77 K, 0.5 T) and B tr (0.92 T at 77 K, 1 T) of the sample were achieved by doping 7 wt% GdY-411 nano-powder, which were enhanced by 48 N and 0.22 T over the undoped sample. The calculated maximum levitation force density of the sample reached up to 19.8 N cm −2 . A B tr of 1.23 T has been recorded finally at 77 K for the GdBCO/CeO 2 contained GdY-411 with 32 mm diameter. The above results demonstrate that the interface defects generated by Gd 2− r Y r -411 nano-particles can serve as effective magnetic flux pinning centers, which enhances the performance of the samples. In addition, compared with the doping of the traditional RE2411, the F L and B tr increased by over 35% and 21%, respectively. Our work provides systematic reference for studying the influence of mixed rare earth type nano-powders on the performance of REBCO bulk superconductor.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"38 12","pages":"125009-125009"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147887523","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}
Pub Date : 2025-08-20DOI: 10.1088/1361-6668/adfd92
Benedikt Berlitz, Etienne Daum, Steffen Deck, Alexey V. Ustinov, Jürgen Lisenfeld
Abstract Superconducting qubits show great promise to realize practical quantum computers from micro-fabricated integrated circuits. However, their solid-state architecture bears the burden of parasitic modes in qubit materials and the control circuitry which cause decoherence and interfere with qubits. Here, we present evidence that wirebonds, which are used to contact the micro-circuits and to realize chip-to-chip airbridges, may contain parasitic Josephson junctions. In our experiment, such a junction was enclosed in a superconducting loop and so gave rise to the formation an RF-SQUID which interfered with a nearby flux-tunable transmon qubit. Periodic signatures observed in magnetic field sweeps revealed a strong AC-dispersive coupling of the parasitic RF-SQUID to both the qubit and its readout resonator, in addition to the DC-inductive coupling between RF-SQUID and qubit. Our finding sheds light on a previously unknown origin of decoherence due to parasitic Josephson junctions in superconducting circuits.
{"title":"Parasitic RF-SQUIDs in superconducting qubits due to wirebonds","authors":"Benedikt Berlitz, Etienne Daum, Steffen Deck, Alexey V. Ustinov, Jürgen Lisenfeld","doi":"10.1088/1361-6668/adfd92","DOIUrl":"https://doi.org/10.1088/1361-6668/adfd92","url":null,"abstract":"Abstract Superconducting qubits show great promise to realize practical quantum computers from micro-fabricated integrated circuits. However, their solid-state architecture bears the burden of parasitic modes in qubit materials and the control circuitry which cause decoherence and interfere with qubits. Here, we present evidence that wirebonds, which are used to contact the micro-circuits and to realize chip-to-chip airbridges, may contain parasitic Josephson junctions. In our experiment, such a junction was enclosed in a superconducting loop and so gave rise to the formation an RF-SQUID which interfered with a nearby flux-tunable transmon qubit. Periodic signatures observed in magnetic field sweeps revealed a strong AC-dispersive coupling of the parasitic RF-SQUID to both the qubit and its readout resonator, in addition to the DC-inductive coupling between RF-SQUID and qubit. Our finding sheds light on a previously unknown origin of decoherence due to parasitic Josephson junctions in superconducting circuits.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"38 9","pages":"095002-095002"},"PeriodicalIF":0.0,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147890005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-01DOI: 10.1088/1361-6668/ade9f4
Manikandan Krishnan, Jiaojiao Meng, Bai-Zhuo Li, Yanming Ma, Cao Wang, Dilip Bhoi, Yoshiya Uwatoko, Qiang Jing, Bo Liu
Abstract Structural, superconducting ground state, and normal state properties on Re-Os-W-Mo-Ta high-entropy alloys (HEAs) were investigated using powder x-ray diffraction, magnetization measurements, electrical resistivity analysis, and specific heat measurements. The structural phase transformation was found to develop through compositional variations of the primary elements of HEAs, leading to the formation of phases such as bcc-type Re 23 Os 5 W 33 Mo 34 Ta 5 , σ -type Re 31 Os 18 W 23 Mo 23 Ta 5 , and α -Mn-type Re 33 Os 34 W 11 Mo 11 Ta 11 . These impurity-free samples, displaying a single-phase structure, exhibit bulk superconducting behavior. Low-temperature specific heat analysis indicates that the bcc-type and σ -type HEAs exhibit weakly coupled, whereas the α -Mn-type HEA exhibits strongly coupled, isotropic and fully gapped superconductivity. Moreover, the stability of bcc-type, σ -type, and α -Mn-type HEAs is significantly influenced by key factors such as valence electron count and electronegativity differences. This study presents observations of structural transformations in HEAs driven by compositional variations without the introduction of additional elements, providing significant insights into the correlation between structural changes and superconducting properties in highly disordered systems.
采用粉末x射线衍射、磁化、电阻率分析和比热等方法研究了Re-Os-W-Mo-Ta高熵合金（HEAs）的结构、超导基态和常态态性能。通过改变HEAs主要元素的组成，形成了bc型Re 23 Os 5 W 33 Mo 34 Ta 5、σ型Re 31 Os 18 W 23 Mo 23 Ta 5和α - mn型Re 33 Os 34 W 11 Mo 11 Ta 11等相。这些无杂质样品，显示单相结构，表现出大块超导行为。低温比热分析表明，bcc型HEA和σ型HEA表现为弱耦合，而α - mn型HEA表现为强耦合、各向同性和全间隙超导。此外，bcc型、σ型和α - mn型HEAs的稳定性受价电子数和电负性差等关键因素的显著影响。本研究展示了在没有引入额外元素的情况下，由成分变化驱动的HEAs结构转变的观察结果，为高度无序系统中结构变化与超导性能之间的相关性提供了重要见解。
{"title":"Evolution of structural dependent superconducting properties on Re-Os-W-Mo-Ta high entropy alloys","authors":"Manikandan Krishnan, Jiaojiao Meng, Bai-Zhuo Li, Yanming Ma, Cao Wang, Dilip Bhoi, Yoshiya Uwatoko, Qiang Jing, Bo Liu","doi":"10.1088/1361-6668/ade9f4","DOIUrl":"https://doi.org/10.1088/1361-6668/ade9f4","url":null,"abstract":"Abstract Structural, superconducting ground state, and normal state properties on Re-Os-W-Mo-Ta high-entropy alloys (HEAs) were investigated using powder x-ray diffraction, magnetization measurements, electrical resistivity analysis, and specific heat measurements. The structural phase transformation was found to develop through compositional variations of the primary elements of HEAs, leading to the formation of phases such as bcc-type Re 23 Os 5 W 33 Mo 34 Ta 5 , σ -type Re 31 Os 18 W 23 Mo 23 Ta 5 , and α -Mn-type Re 33 Os 34 W 11 Mo 11 Ta 11 . These impurity-free samples, displaying a single-phase structure, exhibit bulk superconducting behavior. Low-temperature specific heat analysis indicates that the bcc-type and σ -type HEAs exhibit weakly coupled, whereas the α -Mn-type HEA exhibits strongly coupled, isotropic and fully gapped superconductivity. Moreover, the stability of bcc-type, σ -type, and α -Mn-type HEAs is significantly influenced by key factors such as valence electron count and electronegativity differences. This study presents observations of structural transformations in HEAs driven by compositional variations without the introduction of additional elements, providing significant insights into the correlation between structural changes and superconducting properties in highly disordered systems.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"38 7","pages":"075014-075014"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147882149","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}
Abstract The coupling between non-trivial topology and electron correlations, such as superconductivity, may stimulate novel states of matter, for instance topological and unconventional super-conductivity. Superconductors with a Kagome lattice are such systems, used to study their novel phases and properties. In this work, we studied the SrPb 3 –BaPb 3 family, which possesses both superconductivity and the kagome lattice, by de Haas van Alphen oscillations. For SrPb 3 , the β band is topologically non-trivial, identified by its low effective mass of electron (0.029m 0 ) and non-trivial Berry phase. Slightly Ba doped compounds have the same lattice structure and a new Fermi surface in the band structure due to the down shift of the Fermi level. BaPb 3 has three topologically non-trivial bands and a higher superconducting transition temperature. Our results indicate that the SrPb 3 –BaPb 3 family is an ideal system to study the coupling between topology and superconductivity and deserves further investigations.
{"title":"Study of de Haas van Alphen oscillations on superconducting (Sr,Ba)Pb<sub>3</sub> with Kagome lattice","authors":"Dongyan Xu, Yu Wang, Bin Lei, Guopeng Wang, Yimin Xiong, Mingliang Tian","doi":"10.1088/1361-6668/ade82f","DOIUrl":"https://doi.org/10.1088/1361-6668/ade82f","url":null,"abstract":"Abstract The coupling between non-trivial topology and electron correlations, such as superconductivity, may stimulate novel states of matter, for instance topological and unconventional super-conductivity. Superconductors with a Kagome lattice are such systems, used to study their novel phases and properties. In this work, we studied the SrPb 3 –BaPb 3 family, which possesses both superconductivity and the kagome lattice, by de Haas van Alphen oscillations. For SrPb 3 , the β band is topologically non-trivial, identified by its low effective mass of electron (0.029m 0 ) and non-trivial Berry phase. Slightly Ba doped compounds have the same lattice structure and a new Fermi surface in the band structure due to the down shift of the Fermi level. BaPb 3 has three topologically non-trivial bands and a higher superconducting transition temperature. Our results indicate that the SrPb 3 –BaPb 3 family is an ideal system to study the coupling between topology and superconductivity and deserves further investigations.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"38 7","pages":"075009-075009"},"PeriodicalIF":0.0,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147904354","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}
Pub Date : 2025-06-04DOI: 10.1088/1361-6668/ade0f2
Javier Navarro Montilla, Boon-Kok Tan
Abstract Superconducting travelling-wave parametric amplifiers (TWPAs) play a vital role in a range of high-sensitivity applications. These devices can be realised using various superconducting materials, such as high kinetic inductance films or low-loss transmission lines embedded with discrete nonlinear elements like Josephson junctions (JJs) or superconducting quantum interference devices (SQUIDs), and can operate across different wave-mixing regimes. However, a unifying framework for quick assessment and thus efficiently evaluating the performance of these diverse TWPA architectures, particularly during the design phase, remains lacking. Most existing models are derived from first principles for specific TWPA designs and lack general applicability. While certain simulation program with integrated circuit emphasis (SPICE) tools can more accurately emulate TWPA behaviour post-design, they are typically computationally intensive, time-consuming, and offer limited physical insight; especially regarding key performance-determining factors such as phase matching. This, in turn, impedes the rapid identification of optimal TWPA configurations. In this work, we extend a previously introduced framework for kinetic-inductance (KI-) TWPAs and demonstrate its applicability to a broader class of χ(3) -type TWPA configurations, including bare JJ (JTWPA) and symmetric SQUID-based TWPAs, operating in all wave-mixing modes. This approach facilitates rapid design-space exploration prior to detailed optimisation using SPICE-based simulations. Our method accommodates a wide range of unit cell topologies and meta-material parameters without requiring ground-up derivations from first principles. We validate the framework by comparing it against representative models from the literature, including JJ-, KI-, and DC SQUID-based TWPA designs, and show that it reliably captures the first-order behaviour of their gain–bandwidth characteristics.
{"title":"Extending the kinetic-inductance travelling wave parametric amplifiers coupled-mode framework to other symmetric nonlinear mediums with <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:msup> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>3</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> nonlinearity","authors":"Javier Navarro Montilla, Boon-Kok Tan","doi":"10.1088/1361-6668/ade0f2","DOIUrl":"https://doi.org/10.1088/1361-6668/ade0f2","url":null,"abstract":"Abstract Superconducting travelling-wave parametric amplifiers (TWPAs) play a vital role in a range of high-sensitivity applications. These devices can be realised using various superconducting materials, such as high kinetic inductance films or low-loss transmission lines embedded with discrete nonlinear elements like Josephson junctions (JJs) or superconducting quantum interference devices (SQUIDs), and can operate across different wave-mixing regimes. However, a unifying framework for quick assessment and thus efficiently evaluating the performance of these diverse TWPA architectures, particularly during the design phase, remains lacking. Most existing models are derived from first principles for specific TWPA designs and lack general applicability. While certain simulation program with integrated circuit emphasis (SPICE) tools can more accurately emulate TWPA behaviour post-design, they are typically computationally intensive, time-consuming, and offer limited physical insight; especially regarding key performance-determining factors such as phase matching. This, in turn, impedes the rapid identification of optimal TWPA configurations. In this work, we extend a previously introduced framework for kinetic-inductance (KI-) TWPAs and demonstrate its applicability to a broader class of <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mrow> <mml:msup> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mo stretchy=\"false\">(</mml:mo> <mml:mn>3</mml:mn> <mml:mo stretchy=\"false\">)</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> -type TWPA configurations, including bare JJ (JTWPA) and symmetric SQUID-based TWPAs, operating in all wave-mixing modes. This approach facilitates rapid design-space exploration prior to detailed optimisation using SPICE-based simulations. Our method accommodates a wide range of unit cell topologies and meta-material parameters without requiring ground-up derivations from first principles. We validate the framework by comparing it against representative models from the literature, including JJ-, KI-, and DC SQUID-based TWPA designs, and show that it reliably captures the first-order behaviour of their gain–bandwidth characteristics.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"38 7","pages":"075008-075008"},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147920549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-03DOI: 10.1088/1361-6668/adc8df
Kuan Li, Longfu Li, Lingyong Zeng, Yucheng Li, Rui Chen, Peifeng Yu, Kangwang Wang, Z. Xiang, Tian Shang, Huixia Luo
Abstract Medium/high-entropy alloys (MEAs-HEAs) and rhenium-based compounds with a non-centrosymmetric (NC) structure have received a lot of attention for offering a fertile soil in search for unconventional superconductivity (SC). Here, five previously unreported NC Re-based MEA-HEA superconductors with an α -Mn lattice are successfully synthesized, with their superconducting transition temperatures ( T c s) ranging from 4 to 5 K. An increase in the superconducting transition temperature ( T c ) can be achieved by modulating the valence electron count through compositional adjustments. Magnetization measurements confirm that all the synthesized Re-based MEA-HEAs are bulk type-II superconductors. Specific heat analysis reveals that the superconducting state of these HEAs can be well described by a single-gap s -wave model. Our results show that the Kadowaki–Woods ratio (KWR) of these α -Mn MEA/HEA superconductors are close to the typical value of heavy fermion compounds, suggesting the existence of strong electronic correlation. These findings provide promising material platforms to study the role of high disorder in the origin of SC in the NC MEAs-HEAs.
{"title":"Superconductivity in the medium-entropy/high-entropy Re-based alloys with a non-centrosymmetric <i>α</i>-Mn lattice","authors":"Kuan Li, Longfu Li, Lingyong Zeng, Yucheng Li, Rui Chen, Peifeng Yu, Kangwang Wang, Z. Xiang, Tian Shang, Huixia Luo","doi":"10.1088/1361-6668/adc8df","DOIUrl":"https://doi.org/10.1088/1361-6668/adc8df","url":null,"abstract":"Abstract Medium/high-entropy alloys (MEAs-HEAs) and rhenium-based compounds with a non-centrosymmetric (NC) structure have received a lot of attention for offering a fertile soil in search for unconventional superconductivity (SC). Here, five previously unreported NC Re-based MEA-HEA superconductors with an α -Mn lattice are successfully synthesized, with their superconducting transition temperatures ( T c s) ranging from 4 to 5 K. An increase in the superconducting transition temperature ( T c ) can be achieved by modulating the valence electron count through compositional adjustments. Magnetization measurements confirm that all the synthesized Re-based MEA-HEAs are bulk type-II superconductors. Specific heat analysis reveals that the superconducting state of these HEAs can be well described by a single-gap s -wave model. Our results show that the Kadowaki–Woods ratio (KWR) of these α -Mn MEA/HEA superconductors are close to the typical value of heavy fermion compounds, suggesting the existence of strong electronic correlation. These findings provide promising material platforms to study the role of high disorder in the origin of SC in the NC MEAs-HEAs.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"38 5","pages":"055010-055010"},"PeriodicalIF":0.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://iopscience.iop.org/article/10.1088/1361-6668/adc8df/pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147332714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-03DOI: 10.1088/1361-6668/ad8314
Anna Levochkina, Halima Giovanna Ahmad, P. Mastrovito, I. Chatterjee, Giuseppe Serpico, Luigi Di Palma, Raffaella Ferraiuolo, Roberta Satariano, Pegah Darvehi, Arpit Ranadive, G. Cappelli, Gwenael Le Gal, Luca Planat, Domenico Montemurro, D. Massarotti, F. Tafuri, Nicolas Roch, Guglielmina Pepe, Martina Esposito
Abstract Traveling wave parametric amplifiers (TWPAs) are extensively employed in experiments involving weak microwave signals for their highly desirable quantum-limited and broadband characteristics. However, TWPAs’ broadband nature comes with the disadvantage of admitting the activation of spurious nonlinear processes, such as harmonics generation, that can potentially degrade amplification performance. Here we experimentally investigate a Josephson TWPA device with superconducting nonlinear asymmetric inductive element-based unit cells focusing on the amplification behaviour along with the generation of second and third harmonics of the pump. By comparing experimental results with transient numerical simulations, we demonstrate the influence of Josephson junctions’ fabrication imperfections on the occurrence of harmonics and on the gain behaviour.
{"title":"Investigating pump harmonics generation in a SNAIL-based traveling wave parametric amplifier","authors":"Anna Levochkina, Halima Giovanna Ahmad, P. Mastrovito, I. Chatterjee, Giuseppe Serpico, Luigi Di Palma, Raffaella Ferraiuolo, Roberta Satariano, Pegah Darvehi, Arpit Ranadive, G. Cappelli, Gwenael Le Gal, Luca Planat, Domenico Montemurro, D. Massarotti, F. Tafuri, Nicolas Roch, Guglielmina Pepe, Martina Esposito","doi":"10.1088/1361-6668/ad8314","DOIUrl":"https://doi.org/10.1088/1361-6668/ad8314","url":null,"abstract":"Abstract Traveling wave parametric amplifiers (TWPAs) are extensively employed in experiments involving weak microwave signals for their highly desirable quantum-limited and broadband characteristics. However, TWPAs’ broadband nature comes with the disadvantage of admitting the activation of spurious nonlinear processes, such as harmonics generation, that can potentially degrade amplification performance. Here we experimentally investigate a Josephson TWPA device with superconducting nonlinear asymmetric inductive element-based unit cells focusing on the amplification behaviour along with the generation of second and third harmonics of the pump. By comparing experimental results with transient numerical simulations, we demonstrate the influence of Josephson junctions’ fabrication imperfections on the occurrence of harmonics and on the gain behaviour.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"37 11","pages":"115021-115021"},"PeriodicalIF":0.0,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147906433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1088/1361-6668/ad7646
Wenchao Li, Caida Fu, Chen Guo, He Huang, Chao Yao, Xianping Zhang and Yanwei Ma
Iron-based superconductors with ultra-high upper critical fields and low anisotropy have attracted much attention for superconducting mechanisms and high-field applications. In practical applications, improving the mechanical strength and heat treatment temperature of superconducting tapes is of great significance for the improvement of transport current as well as stability. In this paper, (Ba, K)Fe2As2(Ba-122) superconducting tapes with Cu/Nb/Ag composite sheaths were successfully fabricated using a pre-composite process, which provides a feasible method for the fabrication of high-strength superconducting wires and tapes. It is shown that Cu/Nb/Ag composite sheathed tapes can be sintered at 880 °C, and tapes sintered at 880 °C have the highest transport properties as well as excellent superconductivity of the superconducting cores, as demonstrated by a series of characterizations. In addition, other superconducting properties of the tapes sintered at 880 °C, including grain orientation, flux pinning, upper critical field and irreversible field, were also studied. It was found that none of the three sheaths fractured after sintering and the superconducting core had a high c-axis texture and densities. The high mechanical strength of the Cu/Nb/Ag composite sheathed tape was also demonstrated by comparative tensile experiments. The results indicate that the low-cost Ba-122 tapes with Cu/Nb/Ag composite sheaths hold great promise for future practical applications.
{"title":"Enhanced mechanical strength and texture of (Ba,K)Fe2As2 Cu/Ag composite sheathed tapes with Nb barrier layer","authors":"Wenchao Li, Caida Fu, Chen Guo, He Huang, Chao Yao, Xianping Zhang and Yanwei Ma","doi":"10.1088/1361-6668/ad7646","DOIUrl":"https://doi.org/10.1088/1361-6668/ad7646","url":null,"abstract":"Iron-based superconductors with ultra-high upper critical fields and low anisotropy have attracted much attention for superconducting mechanisms and high-field applications. In practical applications, improving the mechanical strength and heat treatment temperature of superconducting tapes is of great significance for the improvement of transport current as well as stability. In this paper, (Ba, K)Fe2As2(Ba-122) superconducting tapes with Cu/Nb/Ag composite sheaths were successfully fabricated using a pre-composite process, which provides a feasible method for the fabrication of high-strength superconducting wires and tapes. It is shown that Cu/Nb/Ag composite sheathed tapes can be sintered at 880 °C, and tapes sintered at 880 °C have the highest transport properties as well as excellent superconductivity of the superconducting cores, as demonstrated by a series of characterizations. In addition, other superconducting properties of the tapes sintered at 880 °C, including grain orientation, flux pinning, upper critical field and irreversible field, were also studied. It was found that none of the three sheaths fractured after sintering and the superconducting core had a high c-axis texture and densities. The high mechanical strength of the Cu/Nb/Ag composite sheathed tape was also demonstrated by comparative tensile experiments. The results indicate that the low-cost Ba-122 tapes with Cu/Nb/Ag composite sheaths hold great promise for future practical applications.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"187 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255961","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}
Pub Date : 2024-09-11DOI: 10.1088/1361-6668/ad74a1
Elmira Baeva, Anna Kolbatova, Nadezhda Titova, Soham Saha, Alexandra Boltasseva, Simeon Bogdanov, Vladimir M Shalaev, Alexander Semenov, Gregory N Goltsman and Vadim Khrapai
We investigate the effect of various fluctuation mechanisms on the DC resistance in superconducting (SC) devices based on epitaxial titanium nitride (TiN) films. The samples we studied show a relatively steep resistive transition (RT), with a transition width , depending on the film thickness (20 nm, 9 nm, and 5 nm) and device dimensions. This value is significantly broader than expected due to conventional SC fluctuations ( ). The shape and width of the RT can be perfectly described by the well-known effective medium theory, which allows us to understand the origin of the inhomogeneity in the SC properties of TiN films. We propose that this inhomogeneity can have both dynamic and static origins. The dynamic mechanism is associated with spontaneous fluctuations in electron temperature (T-fluctuations), while the static mechanism is due to a random spatial distribution of surface magnetic disorder (MD). Our analysis has revealed clear correlations between the transition width and material parameters as well as device size for both proposed mechanisms. While T-fluctuations may contribute significantly to the observed transition width, our findings suggest that the dominant contribution comes from the MD mechanism. Our results provide new insights into the microscopic origin of broadening of the SC transition and inhomogeneity in thin SC films.
{"title":"Natural width of the superconducting transition in epitaxial TiN films","authors":"Elmira Baeva, Anna Kolbatova, Nadezhda Titova, Soham Saha, Alexandra Boltasseva, Simeon Bogdanov, Vladimir M Shalaev, Alexander Semenov, Gregory N Goltsman and Vadim Khrapai","doi":"10.1088/1361-6668/ad74a1","DOIUrl":"https://doi.org/10.1088/1361-6668/ad74a1","url":null,"abstract":"We investigate the effect of various fluctuation mechanisms on the DC resistance in superconducting (SC) devices based on epitaxial titanium nitride (TiN) films. The samples we studied show a relatively steep resistive transition (RT), with a transition width , depending on the film thickness (20 nm, 9 nm, and 5 nm) and device dimensions. This value is significantly broader than expected due to conventional SC fluctuations ( ). The shape and width of the RT can be perfectly described by the well-known effective medium theory, which allows us to understand the origin of the inhomogeneity in the SC properties of TiN films. We propose that this inhomogeneity can have both dynamic and static origins. The dynamic mechanism is associated with spontaneous fluctuations in electron temperature (T-fluctuations), while the static mechanism is due to a random spatial distribution of surface magnetic disorder (MD). Our analysis has revealed clear correlations between the transition width and material parameters as well as device size for both proposed mechanisms. While T-fluctuations may contribute significantly to the observed transition width, our findings suggest that the dominant contribution comes from the MD mechanism. Our results provide new insights into the microscopic origin of broadening of the SC transition and inhomogeneity in thin SC films.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208372","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}
Pub Date : 2024-09-11DOI: 10.1088/1361-6668/ad7641
Yuwei Zhou, Ge Ye, Shuaishuai Luo, Yu Song, Xin Lu and Huiqiu Yuan
The vanadium-based kagome metals AV3Sb5 (A = K, Rb, and Cs) host a superconducting ground state that coexists with an unconventional charge density wave (CDW). The CDW state exhibits experimental signatures of chirality, electronic nematicity, and time-reversal-symmetry-breaking, raising the questions whether the superconductivity (SC) in AV3Sb5 may also be unconventional, how SC interplays with CDW, and how the two orders evolve upon tuning. This article reviews studies of the superconducting pairing symmetry, and the tuning of SC and CDW in the AV3Sb5 compounds. Various experimental techniques consistently find that CsV3Sb5 exhibits nodeless SC, which remains robust regardless whether the CDW is present. Under hydrostatic pressure, SC in AV3Sb5 becomes enhanced as the CDW is gradually suppressed, revealing a competition between the two orders. In CsV3Sb5, a new CDW state emerges under pressure that competes more strongly with SC relative to the CDW at ambient pressure, and results in two superconducting domes that coexist with CDW. After the CDW in AV3Sb5 is fully suppressed with hydrostatic pressure, a further increase in pressure leads to a nonmonotonic evolution of the superconducting transition temperature driven by lattice modulations. Thickness is shown to be a powerful tuning parameter in AV3Sb5 thin flakes, revealing the evolution of CDW and SC upon dimensional reduction, and can be combined with hydrostatic pressure to shed light on the interplay between SC and CDW. Based on results reviewed in this article, we discuss outstanding issues to be addressed in the AV3Sb5 systems.
{"title":"Kagome materials AV3Sb5 (A = K,Rb,Cs): pairing symmetry and pressure-tuning studies","authors":"Yuwei Zhou, Ge Ye, Shuaishuai Luo, Yu Song, Xin Lu and Huiqiu Yuan","doi":"10.1088/1361-6668/ad7641","DOIUrl":"https://doi.org/10.1088/1361-6668/ad7641","url":null,"abstract":"The vanadium-based kagome metals AV3Sb5 (A = K, Rb, and Cs) host a superconducting ground state that coexists with an unconventional charge density wave (CDW). The CDW state exhibits experimental signatures of chirality, electronic nematicity, and time-reversal-symmetry-breaking, raising the questions whether the superconductivity (SC) in AV3Sb5 may also be unconventional, how SC interplays with CDW, and how the two orders evolve upon tuning. This article reviews studies of the superconducting pairing symmetry, and the tuning of SC and CDW in the AV3Sb5 compounds. Various experimental techniques consistently find that CsV3Sb5 exhibits nodeless SC, which remains robust regardless whether the CDW is present. Under hydrostatic pressure, SC in AV3Sb5 becomes enhanced as the CDW is gradually suppressed, revealing a competition between the two orders. In CsV3Sb5, a new CDW state emerges under pressure that competes more strongly with SC relative to the CDW at ambient pressure, and results in two superconducting domes that coexist with CDW. After the CDW in AV3Sb5 is fully suppressed with hydrostatic pressure, a further increase in pressure leads to a nonmonotonic evolution of the superconducting transition temperature driven by lattice modulations. Thickness is shown to be a powerful tuning parameter in AV3Sb5 thin flakes, revealing the evolution of CDW and SC upon dimensional reduction, and can be combined with hydrostatic pressure to shed light on the interplay between SC and CDW. Based on results reviewed in this article, we discuss outstanding issues to be addressed in the AV3Sb5 systems.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208373","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：