A fully superconducting electron cyclotron resonance （ECR） ion source （SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconductin...A fully superconducting electron cyclotron resonance （ECR） ion source （SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconducting solenoids （Nb-Ti/Cu） and six superconducting sextupoles （Nb-Ti/Cu）. Different from the conventional supercon- ducting ECR magnetic structure, the SEC17AL Ⅱ includes three superconducting solenoid coils＇ that are located inside the superconducting sextupoles. The SECRAL Ⅱ can significantly reduce the interaction forces between the sextupole and the solenoids, and the magnets can also be more compact in size. For this multi-component SECRAL Ⅱ generating its self field of -8 T and being often exposed to the high self field, the mechanical analysis has become the main issue to keep their stress at 〈200 MPa on coils. The analytical and experimental results in mechanics are presented in the SECRAL Ⅱ structure. To improve the accuracy and efficiency of analysis, according to the composite rule of micromechanics, the equivalent uniform windings are used to simulate the epoxy-impregnated Nb-Ti/Cu coils. In addition, using low temperature strain gauges and a wireless fast strain acquisition system, a fundamental experiment on the based on our analysis, the stresses and deformations optimized. strains developments of a sextupole is reported. Finally, for its assembly of each SECRAL Ⅱ coil will be further展开更多
Polycrystalline YBa2Cu3O7-y （YBCO） and Y0.6Gd0.4Ba2-xNbxCu3O7-y （YGBNCO） compounds with 0≤x≤0.225 were synthesized using standard solid state reaction technique. The structure for all samples was characterized b...Polycrystalline YBa2Cu3O7-y （YBCO） and Y0.6Gd0.4Ba2-xNbxCu3O7-y （YGBNCO） compounds with 0≤x≤0.225 were synthesized using standard solid state reaction technique. The structure for all samples was characterized by X-ray difference （XRD） and scanning electron microscopy （SEM）. The transport properties were measured by the （FPP） method in the temperature range from 70 to 130 K. As the Nb content in the samples increased, a diffused phase indicating a niobium perovskite phase and a small amount of unidentified phase appeared. With the increase of Nb content, the superconducting transition temperature Tconset increased slowly with x≤0.125, and then it remained unchanged or slowly decreased with 0.125≤x≤0.225. It could be found that there was a slow decrease of zero-resistance temperature, Tcoffset, with the increase of Nb content. The larger transition width might result from the YBa2NbO6 phase, impurity and unidentified phases of the sample due to the Nb doping.展开更多
Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and t...Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.展开更多
We perform systematic thermal conductivity measurements on heavily hole-doped Ba1-xKxFe2As2 single crystals with 0.747 ≤ x ≤ 0.974. At x=0.747, the K0/T is negligible, indicating a nodeless superconducting gap. A sm...We perform systematic thermal conductivity measurements on heavily hole-doped Ba1-xKxFe2As2 single crystals with 0.747 ≤ x ≤ 0.974. At x=0.747, the K0/T is negligible, indicating a nodeless superconducting gap. A small residual linear term K0/T （=0.035 m W.K-2 cm-1） appears at xz0.826, and it increases slowly up to x=0.974, followed by a substantial increase of more than 20 times to of K0/T clearly shows that the nodal gap appears near x surface topology. The small values of K0/T from x=0.826 the pure KFe2As2 （x=1.0）. This doping dependence = 0.8, possibly associated with the change of Fermi to 0.974 are consistent with the Y-shaped nodal s- wave gap recently revealed by angle-resolved photoemission spectroscopy experiments at x=0.9. Furthermore, the substantial increase of K0/T from x=0.974 to 1.0 is inconsistent with a symmetry-imposed d-wave gap in KFe2 As2, and a possible nodal gap structure in KFe2As2 is discussed.展开更多
Superconductive properties for oxides were predicted by artificial neural network (ANN) method with structural and chemical parameters as inputs. The predicted properties include superconductivity for oxides, distribu...Superconductive properties for oxides were predicted by artificial neural network (ANN) method with structural and chemical parameters as inputs. The predicted properties include superconductivity for oxides, distributed ranges of the superconductive transition temperature (Tc) for complex oxides, and Tc values for cuprate superconductors. The calculated results indicated that the adjusted ANN can be used to predict superconductive properties for unknown oxides.展开更多
The noncentrosymmetric superconductor CaPtAs with time-reversal symmetry breaking in its superconducting state was previously proposed to host nodal superconductivity.Here,by employing ultralow-temperature thermal con...The noncentrosymmetric superconductor CaPtAs with time-reversal symmetry breaking in its superconducting state was previously proposed to host nodal superconductivity.Here,by employing ultralow-temperature thermal conductivity measurement on CaPtAs single crystal,we study its superconducting gap structure.A negligible residual linear term of thermal conductivity(κ_(0)/T)in zero magnetic field and the field dependence ofκ_(0)/T indicate that CaPtAs has multiple superconducting gaps with a dominant s-wave component.This is consistent with recent nuclear quadrupole resonance measurements on CaPtAs.Our work puts a strong constraint on the theories to describe the superconducting pairing symmetry of CaPtAs.展开更多
It was found that selenium doping can suppress the charge-density-wave（CDW） order and induce bulk superconductivity in ZrTe3. The observed superconducting dome suggests the existence of a CDW quantum critical point...It was found that selenium doping can suppress the charge-density-wave（CDW） order and induce bulk superconductivity in ZrTe3. The observed superconducting dome suggests the existence of a CDW quantum critical point（QCP） in ZrTe3-xSex near x ≈ 0.04. To elucidate the superconducting state near the CDW QCP, we measure the thermal conductivity of two ZrTe（3-x）Sex single crystals（x = 0.044 and 0.051） down to 80 m K. For both samples, the residual linear term κ0/T at zero field is negligible, which is a clear evidence for nodeless superconducting gap. Furthermore, the field dependence of κ0/T manifests a multigap behavior. These results demonstrate multiple nodeless superconducting gaps in ZrTe（3-x）Sex,which indicates conventional superconductivity despite of the existence of a CDW QCP.展开更多
The in-plane thermal conductivity of the iron-based superconductor Ca10（Pt4δAs8）（（Fe1-xPtx）2As2）5 single crystal （＂10-4-8＂, Tc = 22 K） was measured down to 80 inK. In a zero field, the residual linear term ...The in-plane thermal conductivity of the iron-based superconductor Ca10（Pt4δAs8）（（Fe1-xPtx）2As2）5 single crystal （＂10-4-8＂, Tc = 22 K） was measured down to 80 inK. In a zero field, the residual linear term ro/T is negligible, suggesting the nodeless superconducting gaps in this multiband compound. In the magnetic fields, r0/T increases rapidly, which mimics the multiband superconductor NbSe2 and LuNi2B2C with highly anisotropic gap. Such a field dependence of K0/T is an evidence for the multiple superconducting gaps with quite different magnitudes or highly anisotropic gap. Compared with the London penetration depth results of the Ca10（Pt3As8）（（Fe1-xPtx）zAs2）5 （＂10-3-8＂） compound, the 10-4-8 and 10-3-8 compounds may have a similar superconducting gap structure.展开更多
As the condensed matter analog of Majorana fermion, the Majorana zero-mode is well known as a building block of fault-tolerant topological quantum computing. This review focuses on the recent progress of Majorana expe...As the condensed matter analog of Majorana fermion, the Majorana zero-mode is well known as a building block of fault-tolerant topological quantum computing. This review focuses on the recent progress of Majorana experiments, especially experiments about semiconductor-superconductor hybrid devices. We first sketch Majorana zero-mode formation from a bottom-up view,which is more suitable for beginners and experimentalists. Then, we survey the status of zero-energy state signatures reported recently, from zero-energy conductance peaks, the oscillations, the quantization, and the interactions with extra degrees of freedom. We also give prospects of future experiments for advancing one-dimensional semiconductor nanowire-superconductor hybrid materials and devices.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11302225the China Postdoctoral Science Foundation under Grant Nos 2014M560820 and 2015T81071
文摘A fully superconducting electron cyclotron resonance （ECR） ion source （SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconducting solenoids （Nb-Ti/Cu） and six superconducting sextupoles （Nb-Ti/Cu）. Different from the conventional supercon- ducting ECR magnetic structure, the SEC17AL Ⅱ includes three superconducting solenoid coils＇ that are located inside the superconducting sextupoles. The SECRAL Ⅱ can significantly reduce the interaction forces between the sextupole and the solenoids, and the magnets can also be more compact in size. For this multi-component SECRAL Ⅱ generating its self field of -8 T and being often exposed to the high self field, the mechanical analysis has become the main issue to keep their stress at 〈200 MPa on coils. The analytical and experimental results in mechanics are presented in the SECRAL Ⅱ structure. To improve the accuracy and efficiency of analysis, according to the composite rule of micromechanics, the equivalent uniform windings are used to simulate the epoxy-impregnated Nb-Ti/Cu coils. In addition, using low temperature strain gauges and a wireless fast strain acquisition system, a fundamental experiment on the based on our analysis, the stresses and deformations optimized. strains developments of a sextupole is reported. Finally, for its assembly of each SECRAL Ⅱ coil will be further
基金Project supported by the Council of the Scientific Research Projects at Konya University
文摘Polycrystalline YBa2Cu3O7-y （YBCO） and Y0.6Gd0.4Ba2-xNbxCu3O7-y （YGBNCO） compounds with 0≤x≤0.225 were synthesized using standard solid state reaction technique. The structure for all samples was characterized by X-ray difference （XRD） and scanning electron microscopy （SEM）. The transport properties were measured by the （FPP） method in the temperature range from 70 to 130 K. As the Nb content in the samples increased, a diffused phase indicating a niobium perovskite phase and a small amount of unidentified phase appeared. With the increase of Nb content, the superconducting transition temperature Tconset increased slowly with x≤0.125, and then it remained unchanged or slowly decreased with 0.125≤x≤0.225. It could be found that there was a slow decrease of zero-resistance temperature, Tcoffset, with the increase of Nb content. The larger transition width might result from the YBa2NbO6 phase, impurity and unidentified phases of the sample due to the Nb doping.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00100 and 2011CBA00200the National Natural Science Foundation of China under Grant Nos 11227904 and 61101012+1 种基金the National High-Technology ResearchDevelopment Program of China under Grant No 2011AA010204the Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves
文摘Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.
基金Supported by the National Basic Research Program under Grant Nos 2012CB821402 and 2015CB921401the National Natural Science Foundation of China+1 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher LearningSTCSM of China(No 15XD1500200)
文摘We perform systematic thermal conductivity measurements on heavily hole-doped Ba1-xKxFe2As2 single crystals with 0.747 ≤ x ≤ 0.974. At x=0.747, the K0/T is negligible, indicating a nodeless superconducting gap. A small residual linear term K0/T （=0.035 m W.K-2 cm-1） appears at xz0.826, and it increases slowly up to x=0.974, followed by a substantial increase of more than 20 times to of K0/T clearly shows that the nodal gap appears near x surface topology. The small values of K0/T from x=0.826 the pure KFe2As2 （x=1.0）. This doping dependence = 0.8, possibly associated with the change of Fermi to 0.974 are consistent with the Y-shaped nodal s- wave gap recently revealed by angle-resolved photoemission spectroscopy experiments at x=0.9. Furthermore, the substantial increase of K0/T from x=0.974 to 1.0 is inconsistent with a symmetry-imposed d-wave gap in KFe2 As2, and a possible nodal gap structure in KFe2As2 is discussed.
文摘Superconductive properties for oxides were predicted by artificial neural network (ANN) method with structural and chemical parameters as inputs. The predicted properties include superconductivity for oxides, distributed ranges of the superconductive transition temperature (Tc) for complex oxides, and Tc values for cuprate superconductors. The calculated results indicated that the adjusted ANN can be used to predict superconductive properties for unknown oxides.
基金Project supported by the National Natural Science Foundation of China (Grant No.12174064)the National Key R&D Program of China (Grant No.2022YFA1402200)the Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)。
文摘The noncentrosymmetric superconductor CaPtAs with time-reversal symmetry breaking in its superconducting state was previously proposed to host nodal superconductivity.Here,by employing ultralow-temperature thermal conductivity measurement on CaPtAs single crystal,we study its superconducting gap structure.A negligible residual linear term of thermal conductivity(κ_(0)/T)in zero magnetic field and the field dependence ofκ_(0)/T indicate that CaPtAs has multiple superconducting gaps with a dominant s-wave component.This is consistent with recent nuclear quadrupole resonance measurements on CaPtAs.Our work puts a strong constraint on the theories to describe the superconducting pairing symmetry of CaPtAs.
基金Project supported by the National Basic Research Program of China(Grant Nos.2012CB821402 and 2015CB921401)the National Natural Science Foundation of China(Grant Nos.91421101,11422429,and 11204312)+1 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,China,STCSM of China(Grant No.15XD1500200)Work at Brookhaven National Laboratory was supported by the US DOE under Contract No.DESC00112704
文摘It was found that selenium doping can suppress the charge-density-wave（CDW） order and induce bulk superconductivity in ZrTe3. The observed superconducting dome suggests the existence of a CDW quantum critical point（QCP） in ZrTe3-xSex near x ≈ 0.04. To elucidate the superconducting state near the CDW QCP, we measure the thermal conductivity of two ZrTe（3-x）Sex single crystals（x = 0.044 and 0.051） down to 80 m K. For both samples, the residual linear term κ0/T at zero field is negligible, which is a clear evidence for nodeless superconducting gap. Furthermore, the field dependence of κ0/T manifests a multigap behavior. These results demonstrate multiple nodeless superconducting gaps in ZrTe（3-x）Sex,which indicates conventional superconductivity despite of the existence of a CDW QCP.
基金supported by the National Basic Research Program of China(Grant No.2012CB821402)the National Natural Science Foundation of China(Grant Nos.11422429 and 91421101)+1 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe Science and Technology Commission of Shanghai Municipality of China(Grant No.15XD1500200)
文摘The in-plane thermal conductivity of the iron-based superconductor Ca10（Pt4δAs8）（（Fe1-xPtx）2As2）5 single crystal （＂10-4-8＂, Tc = 22 K） was measured down to 80 inK. In a zero field, the residual linear term ro/T is negligible, suggesting the nodeless superconducting gaps in this multiband compound. In the magnetic fields, r0/T increases rapidly, which mimics the multiband superconductor NbSe2 and LuNi2B2C with highly anisotropic gap. Such a field dependence of K0/T is an evidence for the multiple superconducting gaps with quite different magnitudes or highly anisotropic gap. Compared with the London penetration depth results of the Ca10（Pt3As8）（（Fe1-xPtx）zAs2）5 （＂10-3-8＂） compound, the 10-4-8 and 10-3-8 compounds may have a similar superconducting gap structure.
基金supported by the National Natural Science Foundation of China (Grant No. 11904399)the Open Research Fund from State Key Laboratory of High Performance Computing of China (Grant No. 201901-09)。
文摘As the condensed matter analog of Majorana fermion, the Majorana zero-mode is well known as a building block of fault-tolerant topological quantum computing. This review focuses on the recent progress of Majorana experiments, especially experiments about semiconductor-superconductor hybrid devices. We first sketch Majorana zero-mode formation from a bottom-up view,which is more suitable for beginners and experimentalists. Then, we survey the status of zero-energy state signatures reported recently, from zero-energy conductance peaks, the oscillations, the quantization, and the interactions with extra degrees of freedom. We also give prospects of future experiments for advancing one-dimensional semiconductor nanowire-superconductor hybrid materials and devices.
