Pub Date : 2024-06-13DOI: 10.1088/1361-6668/ad57fa
Arya Ambadiyil Soman, S. Wimbush, Nick Long, Martin W. Rupich, J. Leveneur, John V. Kennedy, N. Strickland
Particle irradiation offers a route to incorporating additional flux pinning centres in high-temperature superconducting wires with minimal disruption to the pre-existing defect landscape, thereby further enhancing the critical current in a controllable fashion. This work is a comprehensive study of the fluence-dependence of proton irradiation using protons of two energies, 2.5 MeV and 1.2 MeV, in enhancing the critical current performance in commercially available (Y,Dy)Ba2Cu3O7-δ coated conductors. A sequence of fluences covering the range from 1×1015 to 5×1016 protons/cm2 was used in the irradiation process to study the flux pinning in this material. The resulting samples were characterized using field angle-dependent transport critical current measurements over a range of temperatures from 20 K to 77.5 K and magnetic fields up to 8 T, thus covering the wide range of operating conditions. Optimisation of fluence for highest performance at each energy resulted in a similar level of isotropic critical current enhancement, a factor 2.6 improvement at 20 K and 8 T, but with a significant difference in the optimised fluence in each case. The lower energy 1.2 MeV protons produce this enhancement at a three-fold lower fluence compared to 2.5 MeV protons, a result of their higher electronic energy loss. The different samples are analysed within the framework of the maximum entropy model, helping to understand the vortex dynamics before and after irradiation.
粒子辐照为在高温超导线材中加入额外的磁通引脚中心提供了一条途径，而且对原有缺陷景观的破坏最小，从而以可控的方式进一步增强临界电流。这项研究使用 2.5 MeV 和 1.2 MeV 两种能量的质子，全面研究了质子辐照在增强市售 (Y,Dy)Ba2Cu3O7-δ 涂层导体临界电流性能方面的通量依赖性。在辐照过程中使用了一系列从 1×1015 到 5×1016 质子/cm2 的通量来研究这种材料中的通量钉扎现象。在 20 K 至 77.5 K 的温度范围和高达 8 T 的磁场范围内，使用随场角变化的传输临界电流测量法对所得样品进行了表征，从而涵盖了广泛的工作条件。在每种能量下，为获得最高性能而优化通量的结果是，各向同性临界电流得到了类似程度的增强，在 20 K 和 8 T 时提高了 2.6 倍，但在每种情况下，优化通量都存在显著差异。与 2.5 MeV 质子相比，能量较低的 1.2 MeV 质子在较低三倍的通量下就能产生这种增强效果，这是因为它们的电子能量损耗较高。在最大熵模型框架内对不同样品进行分析，有助于了解辐照前后的涡旋动力学。
{"title":"Flux pinning dynamics in optimally proton irradiated REBCO coated conductors","authors":"Arya Ambadiyil Soman, S. Wimbush, Nick Long, Martin W. Rupich, J. Leveneur, John V. Kennedy, N. Strickland","doi":"10.1088/1361-6668/ad57fa","DOIUrl":"https://doi.org/10.1088/1361-6668/ad57fa","url":null,"abstract":"\u0000 Particle irradiation offers a route to incorporating additional flux pinning centres in high-temperature superconducting wires with minimal disruption to the pre-existing defect landscape, thereby further enhancing the critical current in a controllable fashion. This work is a comprehensive study of the fluence-dependence of proton irradiation using protons of two energies, 2.5 MeV and 1.2 MeV, in enhancing the critical current performance in commercially available (Y,Dy)Ba2Cu3O7-δ coated conductors. A sequence of fluences covering the range from 1×1015 to 5×1016 protons/cm2 was used in the irradiation process to study the flux pinning in this material. The resulting samples were characterized using field angle-dependent transport critical current measurements over a range of temperatures from 20 K to 77.5 K and magnetic fields up to 8 T, thus covering the wide range of operating conditions. Optimisation of fluence for highest performance at each energy resulted in a similar level of isotropic critical current enhancement, a factor 2.6 improvement at 20 K and 8 T, but with a significant difference in the optimised fluence in each case. The lower energy 1.2 MeV protons produce this enhancement at a three-fold lower fluence compared to 2.5 MeV protons, a result of their higher electronic energy loss. The different samples are analysed within the framework of the maximum entropy model, helping to understand the vortex dynamics before and after irradiation.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141347512","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}
IInternal Mg diffusion technology (IMD) unfolds the expansive prospect of MgB2 superconducting wires. To the facilitate practical application of IMD, a series of 100 m class MgB2 wires with 18+1 filaments were prepared in this study. Based on the optical micrographs and performances analyses, the annealing temperature, B powder type, and diameter of wires were refined. The results indicated that introducing C-coated B powder into wires would accelerate the diffusion of Mg melt, and enhance Je and layer Jc significantly, while shrinking wire diameter would further improve wires transport capability. The optimal Je and layer Jc of wire in 0.8 mm diameter reached 1.2×104 A/cm2 and 1.1×105 A/cm2 respectively at 4.2 K and 8 T, which contained C-coated B powder and was annealed at 650 ℃. These improved wires were eligible for magnets use in term of performances, integrity, length and uniformity.
内部镁扩散技术（IMD）拓展了 MgB2 超导线材的广阔前景。为了促进内镁扩散技术的实际应用，本研究制备了一系列 100 米级的 18+1 根 MgB2 超导丝。根据光学显微照片和性能分析，对退火温度、B 粉类型和导线直径进行了改进。结果表明，在金属丝中引入 C 包覆的 B 粉可以加速镁熔体的扩散，并显著提高 Je 值和层 Jc 值，而缩小金属丝直径则可以进一步提高金属丝的传输能力。在 4.2 K 和 8 T 条件下，直径为 0.8 mm 的导线的最佳 Je 值和层 Jc 值分别达到了 1.2×104 A/cm2 和 1.1×105 A/cm2 。这些改进后的导线在性能、完整性、长度和均匀性方面都符合磁体的使用要求。
{"title":"Improving superconducting properties of 100 m class MgB2 wire with 18+1 filaments produced via internal Mg diffusion process","authors":"Zhikai Wang, Fang Yang, Qingyang Wang, Dayou Wang, Guo Yan, Pingxaing Zhang","doi":"10.1088/1361-6668/ad570c","DOIUrl":"https://doi.org/10.1088/1361-6668/ad570c","url":null,"abstract":"\u0000 IInternal Mg diffusion technology (IMD) unfolds the expansive prospect of MgB2 superconducting wires. To the facilitate practical application of IMD, a series of 100 m class MgB2 wires with 18+1 filaments were prepared in this study. Based on the optical micrographs and performances analyses, the annealing temperature, B powder type, and diameter of wires were refined. The results indicated that introducing C-coated B powder into wires would accelerate the diffusion of Mg melt, and enhance Je and layer Jc significantly, while shrinking wire diameter would further improve wires transport capability. The optimal Je and layer Jc of wire in 0.8 mm diameter reached 1.2×104 A/cm2 and 1.1×105 A/cm2 respectively at 4.2 K and 8 T, which contained C-coated B powder and was annealed at 650 ℃. These improved wires were eligible for magnets use in term of performances, integrity, length and uniformity.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141357643","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 : 2024-06-11DOI: 10.1088/1361-6668/ad4d5c
E Scarano, E K Arvidsson, A K Roos, E Holmgren, D B Haviland
We study the response of several microwave resonators made from superconducting NbTiN thin-film meandering nanowires with large kinetic inductance, having different circuit topology and coupling to the transmission line. Reflection measurements reveal the parameters of the circuit and analysis of their temperature dependence in the range 1.7–6 K extract the superconducting energy gap and critical temperature. The lumped-element LC resonator, valid in our frequency range of interest, allows us to predict the quasiparticle (QP) contribution to internal loss, independent of circuit topology and characteristic impedance. Our analysis shows that the internal quality factor is limited not by thermal-equilibrium QP, but an additional temperature-dependent source of internal microwave loss.
我们研究了几种由具有大动能电感的超导铌钛氮薄膜蜿蜒纳米线制成的微波谐振器的响应，这些谐振器具有不同的电路拓扑结构以及与传输线的耦合。反射测量揭示了电路参数，并分析了它们在 1.7-6 K 范围内的温度依赖性，从而提取出超导能隙和临界温度。在我们感兴趣的频率范围内有效的叠加元件 LC 谐振器使我们能够预测准粒子 (QP) 对内部损耗的贡献，而与电路拓扑和特性阻抗无关。我们的分析表明，内部品质因数并非受限于热平衡 QP，而是内部微波损耗的另一个随温度变化的来源。
{"title":"Temperature dependence of microwave losses in lumped-element resonators made from superconducting nanowires with high kinetic inductance","authors":"E Scarano, E K Arvidsson, A K Roos, E Holmgren, D B Haviland","doi":"10.1088/1361-6668/ad4d5c","DOIUrl":"https://doi.org/10.1088/1361-6668/ad4d5c","url":null,"abstract":"We study the response of several microwave resonators made from superconducting NbTiN thin-film meandering nanowires with large kinetic inductance, having different circuit topology and coupling to the transmission line. Reflection measurements reveal the parameters of the circuit and analysis of their temperature dependence in the range 1.7–6 K extract the superconducting energy gap and critical temperature. The lumped-element LC resonator, valid in our frequency range of interest, allows us to predict the quasiparticle (QP) contribution to internal loss, independent of circuit topology and characteristic impedance. Our analysis shows that the internal quality factor is limited not by thermal-equilibrium QP, but an additional temperature-dependent source of internal microwave loss.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524327","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 : 2024-06-11DOI: 10.1088/1361-6668/ad4a34
Arpit Kumar Srivastava, Enric Pardo
High-temperature REBCO superconducting tapes are very promising for high-field magnets. With high magnetic field applications there are high electromechanical forces, and thus a concern for mechanical damage. Due to the presence of large screening currents and the composite structure of the tape, the mechanical design of these magnets is not straightforward. In addition, many contemporary designs use insulated winding. In this work, we develop a novel two-dimensional axi-symmetric finite element tool programmed in MATLAB that assumes the displacement field to be within a linear elastic range. The stack of pancakes and the large number of REBCO tape turns are approximated as an anisotropic bulk hollow cylinder. Our results agree with uni-axial stress experiments in the literature, validating the bulk approximation. Here, we study the following configuration. The current is first ramped up to below the critical current and we calculate the screening currents and the forces that they cause using the minimum electromagnetic entropy production method (MEMEP) model. This electromagnetic model can now take insulated magnets into account. As a case study, a 32 T REBCO superconductor magnet is simulated numerically. We perform a complete mechanical analysis of the magnet by including the axial and shear mechanical quantities for each pancake, unlike in previous work where only radial and circumferential quantities were focused on. The effect on mechanical quantities without the screening current is also calculated and compared. It is shown that including the screening current-induced field strongly affects the mechanical quantities, especially the shear stress. The latter may be a critical quantity for certain magnet configurations. Additionally, in order to overcome high stresses, a stiff overbanding of different materials is considered and numerically modelled, which significantly reduces the mechanical stresses. The finite element-based model developed is efficient in calculating the mechanical behaviour of any general superconductor magnet and its devices.
{"title":"Modelling the mechanics of 32 T REBCO superconductor magnet using numerical simulation","authors":"Arpit Kumar Srivastava, Enric Pardo","doi":"10.1088/1361-6668/ad4a34","DOIUrl":"https://doi.org/10.1088/1361-6668/ad4a34","url":null,"abstract":"High-temperature REBCO superconducting tapes are very promising for high-field magnets. With high magnetic field applications there are high electromechanical forces, and thus a concern for mechanical damage. Due to the presence of large screening currents and the composite structure of the tape, the mechanical design of these magnets is not straightforward. In addition, many contemporary designs use insulated winding. In this work, we develop a novel two-dimensional axi-symmetric finite element tool programmed in MATLAB that assumes the displacement field to be within a linear elastic range. The stack of pancakes and the large number of REBCO tape turns are approximated as an anisotropic bulk hollow cylinder. Our results agree with uni-axial stress experiments in the literature, validating the bulk approximation. Here, we study the following configuration. The current is first ramped up to below the critical current and we calculate the screening currents and the forces that they cause using the minimum electromagnetic entropy production method (MEMEP) model. This electromagnetic model can now take insulated magnets into account. As a case study, a 32 T REBCO superconductor magnet is simulated numerically. We perform a complete mechanical analysis of the magnet by including the axial and shear mechanical quantities for each pancake, unlike in previous work where only radial and circumferential quantities were focused on. The effect on mechanical quantities without the screening current is also calculated and compared. It is shown that including the screening current-induced field strongly affects the mechanical quantities, especially the shear stress. The latter may be a critical quantity for certain magnet configurations. Additionally, in order to overcome high stresses, a stiff overbanding of different materials is considered and numerically modelled, which significantly reduces the mechanical stresses. The finite element-based model developed is efficient in calculating the mechanical behaviour of any general superconductor magnet and its devices.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524326","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 : 2024-06-11DOI: 10.1088/1361-6668/ad570d
Sung Hoon Lee, Yoon Seok Chae, Ho-min Kim, Huu Luong Quach, Ji Hyung Kim
This study examined the turn-to-turn contact resistance (Rct) between rare-earth barium copper oxide (REBCO) tapes and layers of vanadium trioxide (V2O3) and V2O3 mixed with metal powder mixture. V2O3 in single crystal structure was electrically characterised to exhibit resistivity with negative temperature dependence, allowing the turn-to-turn insulation to self-regulate the current bypass between REBCO tapes. To facilitate effective quench protection of V2O3-insulated REBCO magnets above the metal-insulator transition temperature (Trt), Rct must be further reduced to a level similar to those of non- and metal as insulated (NI and MI) REBCO magnets. Thus, we explored the mixing of conductive metal powders such as molybdenum (Mo) with V2O3 paste and investigated the transition properties of Rct. The resistance versus temperature characteristics, microscopic morphologies of the V2O3 layers, and thermal conductivity (kv) were appropriately assessed to determine the effects of mixing the metal powder with V2O3. The Rct of virgin V2O3 exhibited variations of 107–105 μΩ·cm2 under 77–293 K. As the mixing concentration of the metal powder was increased, the reduction magnitude on Rct increased for > Trt (approximately 150 K). Furthermore, the transition slope became gentler for a wider temperature range of < Trt. For metal powder concentrations exceeding 50 wt%, Rct decreased by approximately 2 orders of magnitude (~103 μΩ·cm2) for > 150 K compared with that for virgin V2O3 paste. Moreover, compared to that of pure V2O3, kv demonstrated a remarkable increase of approximately 352% at 91 K fore Mo powder mixed at a concentration of 60 wt%. The improved electrical and thermal properties of the V2O3 insulation layer owing to the mixing of metal powders can help REBCO magnets operate in an insulated state under normal conditions and effectively convert to a non-insulated state under quenching.
{"title":"Investigation on characteristic of vanadium trioxide insulation mixed with metal powder for rare-earth barium copper oxide coils","authors":"Sung Hoon Lee, Yoon Seok Chae, Ho-min Kim, Huu Luong Quach, Ji Hyung Kim","doi":"10.1088/1361-6668/ad570d","DOIUrl":"https://doi.org/10.1088/1361-6668/ad570d","url":null,"abstract":"\u0000 This study examined the turn-to-turn contact resistance (Rct) between rare-earth barium copper oxide (REBCO) tapes and layers of vanadium trioxide (V2O3) and V2O3 mixed with metal powder mixture. V2O3 in single crystal structure was electrically characterised to exhibit resistivity with negative temperature dependence, allowing the turn-to-turn insulation to self-regulate the current bypass between REBCO tapes. To facilitate effective quench protection of V2O3-insulated REBCO magnets above the metal-insulator transition temperature (Trt), Rct must be further reduced to a level similar to those of non- and metal as insulated (NI and MI) REBCO magnets. Thus, we explored the mixing of conductive metal powders such as molybdenum (Mo) with V2O3 paste and investigated the transition properties of Rct. The resistance versus temperature characteristics, microscopic morphologies of the V2O3 layers, and thermal conductivity (kv) were appropriately assessed to determine the effects of mixing the metal powder with V2O3. The Rct of virgin V2O3 exhibited variations of 107–105 μΩ·cm2 under 77–293 K. As the mixing concentration of the metal powder was increased, the reduction magnitude on Rct increased for > Trt (approximately 150 K). Furthermore, the transition slope became gentler for a wider temperature range of < Trt. For metal powder concentrations exceeding 50 wt%, Rct decreased by approximately 2 orders of magnitude (~103 μΩ·cm2) for > 150 K compared with that for virgin V2O3 paste. Moreover, compared to that of pure V2O3, kv demonstrated a remarkable increase of approximately 352% at 91 K fore Mo powder mixed at a concentration of 60 wt%. The improved electrical and thermal properties of the V2O3 insulation layer owing to the mixing of metal powders can help REBCO magnets operate in an insulated state under normal conditions and effectively convert to a non-insulated state under quenching.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141358134","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 : 2024-06-10DOI: 10.1088/1361-6668/ad5627
V. Zakosarenko, M. Schmelz, Jurgen Kunert, Evgeni Il'ichev, R. Stolz
Noise in superconducting quantum interference devices (dc SQUIDs) with different design, based on Nb/AlOx/Nb technology, has been systematically measured at temperature T = 4.2 K. We demonstrate that for all our devices the power spectral density of the white noise (above a frequency of about 1 kHz) is determined by the shunt resistors, reaching about 5 times Planck’s constant. The low-frequency noise level was measured for washer- and multi-loop-type SQUIDs with systematically varied effective area, SQUID loop perimeter, and inductance. We show that at 1 Hz the noise spectral density is approximately 40 times higher than the white noise level and its scaling with washer width and effective area is negligible. These results are incompatible with several models of the flicker noise source. Possible origins of this noise are discussed.
我们在温度 T = 4.2 K 的条件下对基于铌/氧化铝/铌技术的不同设计的超导量子干涉装置（直流 SQUID）中的噪声进行了系统测量。我们证明，对于我们的所有装置，白噪声（频率高于约 1 kHz）的功率谱密度由分流电阻决定，约为普朗克常数的 5 倍。我们测量了有效面积、SQUID 回路周长和电感量系统变化的洗碗机型和多回路型 SQUID 的低频噪声水平。我们的研究表明，在 1 Hz 时，噪声频谱密度比白噪声水平高出约 40 倍，而且其与垫圈宽度和有效面积的比例关系可以忽略不计。这些结果与若干闪烁噪声源模型不符。本文讨论了这种噪声的可能来源。
{"title":"Design dependence of noise in Nb-based dc SQUIDs","authors":"V. Zakosarenko, M. Schmelz, Jurgen Kunert, Evgeni Il'ichev, R. Stolz","doi":"10.1088/1361-6668/ad5627","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5627","url":null,"abstract":"\u0000 Noise in superconducting quantum interference devices (dc SQUIDs) with different design, based on Nb/AlOx/Nb technology, has been systematically measured at temperature T = 4.2 K. We demonstrate that for all our devices the power spectral density of the white noise (above a frequency of about 1 kHz) is determined by the shunt resistors, reaching about 5 times Planck’s constant. The low-frequency noise level was measured for washer- and multi-loop-type SQUIDs with systematically varied effective area, SQUID loop perimeter, and inductance. We show that at 1 Hz the noise spectral density is approximately 40 times higher than the white noise level and its scaling with washer width and effective area is negligible. These results are incompatible with several models of the flicker noise source. Possible origins of this noise are discussed.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141365858","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 : 2024-06-10DOI: 10.1088/1361-6668/ad50af
M V Shibalov, I M Asharchuk, E O Epifanov, I V Trofimov, A M Mumlyakov, N V Minaev, Y V Anufriev, M A Tarkhov
This paper presents the development of a superconducting nanowire single-photon detector (SNSPD) integrated into a distributed Bragg reflector (DBR) with a design center wavelength of 830 nm and a bandwidth of 200 nm. This SNSPD is made of a superconducting niobium nitride (NbN) thin film that is produced using plasma-enhanced atomic layer deposition. The DBR is made of 15 alternating layers of silicon nitride and silicon oxide that are produced through plasma-enhanced chemical vapor deposition. The reflection efficiency of the mirror is 90% at a wavelength of 830 nm. For sufficient optical coupling, an optical micro-connector optimized for multimode or single-mode optical fibers with a diameter of 128 μm was formed using two-photon polymerization techniques. The niobium nitride film was deposited onto the DBR surface in-situ in two separate reactors connected by a vacuum transfer. The in-situ technique of deposition of a superconducting niobium nitride film and a DBR has allowed achieving a system detection efficiency of 90% at a wavelength of 830 nm and a dark count rate of 10 s−1 at a temperature of 2.5 K. Additionally, the detector jitter was 50 ps.
{"title":"Superconducting single-photon detector integrated in DBR with optical microconnector for MM or SM fiber","authors":"M V Shibalov, I M Asharchuk, E O Epifanov, I V Trofimov, A M Mumlyakov, N V Minaev, Y V Anufriev, M A Tarkhov","doi":"10.1088/1361-6668/ad50af","DOIUrl":"https://doi.org/10.1088/1361-6668/ad50af","url":null,"abstract":"This paper presents the development of a superconducting nanowire single-photon detector (SNSPD) integrated into a distributed Bragg reflector (DBR) with a design center wavelength of 830 nm and a bandwidth of 200 nm. This SNSPD is made of a superconducting niobium nitride (NbN) thin film that is produced using plasma-enhanced atomic layer deposition. The DBR is made of 15 alternating layers of silicon nitride and silicon oxide that are produced through plasma-enhanced chemical vapor deposition. The reflection efficiency of the mirror is 90% at a wavelength of 830 nm. For sufficient optical coupling, an optical micro-connector optimized for multimode or single-mode optical fibers with a diameter of 128 <italic toggle=\"yes\">μ</italic>m was formed using two-photon polymerization techniques. The niobium nitride film was deposited onto the DBR surface <italic toggle=\"yes\">in-situ</italic> in two separate reactors connected by a vacuum transfer. The <italic toggle=\"yes\">in-situ</italic> technique of deposition of a superconducting niobium nitride film and a DBR has allowed achieving a system detection efficiency of 90% at a wavelength of 830 nm and a dark count rate of 10 s<sup>−1</sup> at a temperature of 2.5 K. Additionally, the detector jitter was 50 ps.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141532057","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 : 2024-06-10DOI: 10.1088/1361-6668/ad4b61
Daniel Pérez Lozano, Jean-Philippe Soulié, Blake Hodges, Xiaoyu Piao, Sabine O’Neal, Anne-Marie Valente-Feliciano, Quentin Herr, Zsolt Tőkei, Min-Soo Kim, Anna Herr
Scaling superconducting digital circuits requires fundamental changes in the current material set and fabrication process. The transition to 300 mm wafers and the implementation of advanced lithography are instrumental in facilitating mature CMOS processes, ensuring uniformity, and optimizing the yield. This study explores the properties of NbxTi(1−x)N films fabricated by magnetron DC sputtering on 300 mm Si wafers. As a promising alternative to traditional Nb in device manufacturing, NbxTi(1−x)N offers numerous advantages, including enhanced stability and scalability to smaller dimensions, in both processing and design. As a ternary material, NbxTi(1−x)N allows engineering material parameters by changing deposition conditions. The engineered properties can be used to modulate device parameters through the stack and mitigate failure modes. We report characterization of NbxTi(1−x)N films at less than 2% thickness variability, 2.4% Tc variability and 3% composition variability. Film resistivity (140–375 Ωcm) shows a strong correlation with the film oxygen content, while the critical temperature Tc (4.6 K–14.1 K) is strongly affected by film stoichiometry and its microstructure has only a moderate effect on modifying Tc. Our results offer insights about the interplay between film stoichiometry, film microstructure and critical temperature.
{"title":"Properties of Nb x Ti(1−x)N thin films deposited on 300 mm silicon wafers for upscaling superconducting digital circuits","authors":"Daniel Pérez Lozano, Jean-Philippe Soulié, Blake Hodges, Xiaoyu Piao, Sabine O’Neal, Anne-Marie Valente-Feliciano, Quentin Herr, Zsolt Tőkei, Min-Soo Kim, Anna Herr","doi":"10.1088/1361-6668/ad4b61","DOIUrl":"https://doi.org/10.1088/1361-6668/ad4b61","url":null,"abstract":"Scaling superconducting digital circuits requires fundamental changes in the current material set and fabrication process. The transition to 300 mm wafers and the implementation of advanced lithography are instrumental in facilitating mature CMOS processes, ensuring uniformity, and optimizing the yield. This study explores the properties of Nb<italic toggle=\"yes\">\u0000<sub>x</sub>\u0000</italic>Ti<sub>(1−<italic toggle=\"yes\">x</italic>)</sub>N films fabricated by magnetron DC sputtering on 300 mm Si wafers. As a promising alternative to traditional Nb in device manufacturing, Nb<italic toggle=\"yes\">\u0000<sub>x</sub>\u0000</italic>Ti<sub>(1−<italic toggle=\"yes\">x</italic>)</sub>N offers numerous advantages, including enhanced stability and scalability to smaller dimensions, in both processing and design. As a ternary material, Nb<italic toggle=\"yes\">\u0000<sub>x</sub>\u0000</italic>Ti<sub>(1−<italic toggle=\"yes\">x</italic>)</sub>N allows engineering material parameters by changing deposition conditions. The engineered properties can be used to modulate device parameters through the stack and mitigate failure modes. We report characterization of Nb<italic toggle=\"yes\">\u0000<sub>x</sub>\u0000</italic>Ti<sub>(1−<italic toggle=\"yes\">x</italic>)</sub>N films at less than 2% thickness variability, 2.4% <italic toggle=\"yes\">T</italic>\u0000<sub>c</sub> variability and 3% composition variability. Film resistivity (140–375 Ωcm) shows a strong correlation with the film oxygen content, while the critical temperature <italic toggle=\"yes\">T</italic>\u0000<sub>c</sub> (4.6 K–14.1 K) is strongly affected by film stoichiometry and its microstructure has only a moderate effect on modifying <italic toggle=\"yes\">T</italic>\u0000<sub>c</sub>. Our results offer insights about the interplay between film stoichiometry, film microstructure and critical temperature.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141532055","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}
We attempted to improve the critical current density Jc under a longitudinal magnetic field (LMF) by using columnar defects (CDs) tilted toward the transport current, where the CDs were produced with 80 MeV Xe ions at an incident angle(s) up to φi = 87.5° relative to the c-axis of YBa2Cu3Oy thin films. The formation of CDs extending throughout the film was confirmed by cross-sectional transmission electron microscopy. The CDs tilted at φi = 87.5° weakened the magnetic field dependence of Jc under the LMF, providing a Jc higher than that of the unirradiated film in a high magnetic field. This is the first study to demonstrate that CDs and/or irradiation defects contribute to flux pinning under the LMF in high-Tc superconductors. In addition, the Jc under LMF was sensitive to the tilt angle of the CDs: the Jc was reduced by CDs tilted not only at φi = 0°, but also at a slightly larger angle relative to the ab-plane, i.e. φi = 85°. The introduction of CDs rather disturbs the LMF effect because of the large volume passing through the film thickness, unless the tilt angles of the CDs are within the narrow angular region effective for the LMF effect.
我们试图通过使用向传输流倾斜的柱状缺陷（CD）来提高纵向磁场（LMF）下的临界电流密度Jc，其中CD是用80 MeV Xe离子在相对于YBa2Cu3Oy薄膜c轴最大φi = 87.5°的入射角下产生的。横截面透射电子显微镜证实了延伸至整个薄膜的光盘的形成。以 φi = 87.5° 倾斜的光盘削弱了 LMF 下 Jc 的磁场依赖性，使其在高磁场中的 Jc 值高于未受辐照薄膜的 Jc 值。这是首次研究证明 CD 和/或辐照缺陷有助于高锝超导体在低磁场下的磁通钉住。此外，LMF 下的 Jc 对 CD 的倾斜角度很敏感：不仅在 φi = 0° 倾斜的 CD 会降低 Jc，而且在相对于 ab 平面稍大的角度（即 φi = 85°）倾斜的 CD 也会降低 Jc。由于穿过薄膜厚度的体积较大，除非 CD 的倾斜角在对 LMF 效应有效的狭窄角度区域内，否则 CD 的引入会对 LMF 效应造成干扰。
{"title":"Tuning critical current density properties of YBa2Cu3O y thin films under longitudinal magnetic field by using heavy-ion irradiation","authors":"Tetsuro Sueyoshi, Ryusei Enokihata, Hiroshi Yamaguchi, Satoshi Semboshi, Toshinori Ozaki, Hitoshi Sakane, Terukazu Nishizaki, Norito Ishikawa","doi":"10.1088/1361-6668/ad51ae","DOIUrl":"https://doi.org/10.1088/1361-6668/ad51ae","url":null,"abstract":"We attempted to improve the critical current density <italic toggle=\"yes\">J</italic>\u0000<sub>c</sub> under a longitudinal magnetic field (LMF) by using columnar defects (CDs) tilted toward the transport current, where the CDs were produced with 80 MeV Xe ions at an incident angle(s) up to <italic toggle=\"yes\">φ</italic>\u0000<sub>i</sub> = 87.5° relative to the <italic toggle=\"yes\">c</italic>-axis of YBa<sub>2</sub>Cu<sub>3</sub>O<italic toggle=\"yes\">\u0000<sub>y</sub>\u0000</italic> thin films. The formation of CDs extending throughout the film was confirmed by cross-sectional transmission electron microscopy. The CDs tilted at <italic toggle=\"yes\">φ</italic>\u0000<sub>i</sub> = 87.5° weakened the magnetic field dependence of <italic toggle=\"yes\">J</italic>\u0000<sub>c</sub> under the LMF, providing a <italic toggle=\"yes\">J</italic>\u0000<sub>c</sub> higher than that of the unirradiated film in a high magnetic field. This is the first study to demonstrate that CDs and/or irradiation defects contribute to flux pinning under the LMF in high-<italic toggle=\"yes\">T</italic>\u0000<sub>c</sub> superconductors. In addition, the <italic toggle=\"yes\">J</italic>\u0000<sub>c</sub> under LMF was sensitive to the tilt angle of the CDs: the <italic toggle=\"yes\">J</italic>\u0000<sub>c</sub> was reduced by CDs tilted not only at <italic toggle=\"yes\">φ</italic>\u0000<sub>i</sub> = 0°, but also at a slightly larger angle relative to the <italic toggle=\"yes\">ab</italic>-plane, i.e. <italic toggle=\"yes\">φ</italic>\u0000<sub>i</sub> = 85°. The introduction of CDs rather disturbs the LMF effect because of the large volume passing through the film thickness, unless the tilt angles of the CDs are within the narrow angular region effective for the LMF effect.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141532056","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}
This paper proposes the novel concept and method of the feed line resonator (FLR). By introducing the external quality factor adjusting line, the feed lines can be transformed to resonators, and can be used not only for providing external coupling, as well as generate extra transmission poles in the passband. The conditions for generating transmission poles by using the FLR are systematically investigated. The key advancement of the FLR method is that extra transmission poles are introduced, without increase the number of conventional resonators, the filter bandwidth can be extended and the selectivity also improved. The triple-mode FLR was proposed which can realize six extra transmission poles in the pass band and n transmission zeros out-of-band. A five-section multi-mode resonator proposed for wideband filter. Single-, two-, three- and four-stage wideband superconducting filters were designed to demonstrate the FLR method. These filters exhibit extreme sharp skirts, the attenuation slop at lower and higher band can reach 273.9 dB/GHz and 523.7 dB/GHz, respectively. The passband is from 2.26 GHz to 5.54 GHz with the FBW (fractional bandwidth) of 95 %. The measure results agree well with the simulated ones.
{"title":"The feed line resonator (FLR) method and it’s application to superconducting wideband filter design with extreme sharp skirt","authors":"Xilong Lu, Rui Zhang, Qingyu Kong, Shi-gang Zhou, Xudong Bai, Liguo Zhou, Guangsong Wei, Xueyang Fang","doi":"10.1088/1361-6668/ad5628","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5628","url":null,"abstract":"\u0000 This paper proposes the novel concept and method of the feed line resonator (FLR). By introducing the external quality factor adjusting line, the feed lines can be transformed to resonators, and can be used not only for providing external coupling, as well as generate extra transmission poles in the passband. The conditions for generating transmission poles by using the FLR are systematically investigated. The key advancement of the FLR method is that extra transmission poles are introduced, without increase the number of conventional resonators, the filter bandwidth can be extended and the selectivity also improved. The triple-mode FLR was proposed which can realize six extra transmission poles in the pass band and n transmission zeros out-of-band. A five-section multi-mode resonator proposed for wideband filter. Single-, two-, three- and four-stage wideband superconducting filters were designed to demonstrate the FLR method. These filters exhibit extreme sharp skirts, the attenuation slop at lower and higher band can reach 273.9 dB/GHz and 523.7 dB/GHz, respectively. The passband is from 2.26 GHz to 5.54 GHz with the FBW (fractional bandwidth) of 95 %. The measure results agree well with the simulated ones.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366314","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}
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