In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperat...In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperature(T_(c))of 1D superconductors is low.In this work,we theoretically investigate the possible high T_(c) superconductivity of(5,5)carbon nanotube(CNT).The pristine(5,5)CNT is a Dirac semimetal and can be modulated into a semiconductor by full hydrogenation.Interestingly,by further hole doping,it can be regulated into a metallic state with the sp^(3)-hybridized σ electrons metalized,and a giant Kohn anomaly appears in the optical phonons.The two factors together enhance the electron–phonon coupling,and lead to high-T_(c) superconductivity.When the hole doping concentration of hydrogenated-(5,5)CNT is 2.5 hole/cell,the calculated T_(c) is 82.3 K,exceeding the boiling point of liquid nitrogen.Therefore,the predicted hole-doped hydrogenated-(5,5)CNT provides a new platform for 1D high-T_(c) superconductivity and may have potential applications in 1D nanodevices.展开更多
Temperature-dependent resistivity,upper critical field H_(c2)and its anisotropy in overdoped superconducting Ba_(1-x)K_x Fe_2As_2(x=0.6-1)single crystals have been measured in steady magnetic fields up to 44 T and low...Temperature-dependent resistivity,upper critical field H_(c2)and its anisotropy in overdoped superconducting Ba_(1-x)K_x Fe_2As_2(x=0.6-1)single crystals have been measured in steady magnetic fields up to 44 T and low temperatures down to 0.4 K.Analysis using both the quadratic term and power-law fitting demonstrates that the in-plane resistivityρ_(ab)(T)progressively approaches the Fermi-liquid T~2behavior with increasing K doping and reaches a saturation plateau at x≈0.8.The temperature dependence of both H_(c2)^(ab)and H^(c)_(c2)follows the Werthamer-Helfand-Hohenberg model,incorporating orbital and spin paramagnetic effects.For x≤0.8,the orbital effect dominates for H ab,while the Pauli paramagnetic effect prevails for H c.For x>0.8,the Pauli paramagnetic effect becomes dominant in both crystallographic directions.The anisotropy of H_(c2)(0)exhibits a discontinuity in its dependence on K doping concentration with a significant enhancement at x=0.8 and a maximum at x=0.9.These experimental results indicate that the electron correlation effect is enhanced in the heavily overdoped Ba_(1-x)K_(x)Fe_(2)As_(2)system where the underlying symmetries are broken due to the Fermi surface reconstruction before x=0.9.展开更多
We report a comprehensive investigation of the superconducting properties of the mineral superconductor covellite(Cu S)using high-quality single crystals.First,we establish that Cu S is an intrinsic type-Ⅱsuperconduc...We report a comprehensive investigation of the superconducting properties of the mineral superconductor covellite(Cu S)using high-quality single crystals.First,we establish that Cu S is an intrinsic type-Ⅱsuperconductor,correcting its long-standing classification as type-Ⅰ.Second,a complete set of anisotropic superconducting parameters is determined,including the critical fields,penetration depth and coherence length,which yield a Ginzburg–Landau parameterκ~1.5 and a moderate anisotropy ofγ~2.Our results indicate that this type-Ⅱsuperconductivity can be well-described by a conventional,weak-coupling,single-band s-wave pairing mechanism.This work fills a long-standing gap in the understanding of this archetypal superconductor.展开更多
The spatially-resolved laser-based high resolution angle resolved photoemission spectroscopy(ARPES)measurements have been performed on the optimally-doped HgBa_(2)Ca_(2)Cu_(3)O_(8+δ)(Hg1223)superconductor with a T_(c...The spatially-resolved laser-based high resolution angle resolved photoemission spectroscopy(ARPES)measurements have been performed on the optimally-doped HgBa_(2)Ca_(2)Cu_(3)O_(8+δ)(Hg1223)superconductor with a T_(c) of 133 K.Two distinct regions are identified on the cleaved surface:the single Fermi surface region where only one Fermi surface is observed,and the double Fermi surface region where two Fermi surface sheets are resolved coming from both the inner(IP)and outer(OP)CuO_(2) planes.The electronic structure and superconducting gap are measured on both of these two regions.In both cases,the observed electronic states are mainly concentrated near the nodal region.The momentum dependence of the superconducting gap deviates from the standard d-wave form.These results indicate that the surface electronic structure of Hg1223 behaves more like that of underdoped cuprates.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12074213 and 11574108)the Major Basic Program of Natural Science Foundation of Shandong Province (Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province (Grant No.ZR2023MA082)。
文摘In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperature(T_(c))of 1D superconductors is low.In this work,we theoretically investigate the possible high T_(c) superconductivity of(5,5)carbon nanotube(CNT).The pristine(5,5)CNT is a Dirac semimetal and can be modulated into a semiconductor by full hydrogenation.Interestingly,by further hole doping,it can be regulated into a metallic state with the sp^(3)-hybridized σ electrons metalized,and a giant Kohn anomaly appears in the optical phonons.The two factors together enhance the electron–phonon coupling,and lead to high-T_(c) superconductivity.When the hole doping concentration of hydrogenated-(5,5)CNT is 2.5 hole/cell,the calculated T_(c) is 82.3 K,exceeding the boiling point of liquid nitrogen.Therefore,the predicted hole-doped hydrogenated-(5,5)CNT provides a new platform for 1D high-T_(c) superconductivity and may have potential applications in 1D nanodevices.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1611100,2023YFA1406100,and 2018YFA0704201)the Systematic Fundamental Research Program Leveraging Major Scientific and Technological Infrastructure,Chinese Academy of Sciences(Grant No.JZHKYPT-2021-08)+1 种基金the National Natural Science Foundation of China(Grant Nos.11704385,11874359,and 12274444)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)。
文摘Temperature-dependent resistivity,upper critical field H_(c2)and its anisotropy in overdoped superconducting Ba_(1-x)K_x Fe_2As_2(x=0.6-1)single crystals have been measured in steady magnetic fields up to 44 T and low temperatures down to 0.4 K.Analysis using both the quadratic term and power-law fitting demonstrates that the in-plane resistivityρ_(ab)(T)progressively approaches the Fermi-liquid T~2behavior with increasing K doping and reaches a saturation plateau at x≈0.8.The temperature dependence of both H_(c2)^(ab)and H^(c)_(c2)follows the Werthamer-Helfand-Hohenberg model,incorporating orbital and spin paramagnetic effects.For x≤0.8,the orbital effect dominates for H ab,while the Pauli paramagnetic effect prevails for H c.For x>0.8,the Pauli paramagnetic effect becomes dominant in both crystallographic directions.The anisotropy of H_(c2)(0)exhibits a discontinuity in its dependence on K doping concentration with a significant enhancement at x=0.8 and a maximum at x=0.9.These experimental results indicate that the electron correlation effect is enhanced in the heavily overdoped Ba_(1-x)K_(x)Fe_(2)As_(2)system where the underlying symmetries are broken due to the Fermi surface reconstruction before x=0.9.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1611102,2022YFA1403903,2022YFA1602802,and 2023YFA1406101)the National Natural Science Foundation of China(Grant No.12304075)CAS Project for Young Scientists in Basic Research(Grant No.2022YSBR-048)。
文摘We report a comprehensive investigation of the superconducting properties of the mineral superconductor covellite(Cu S)using high-quality single crystals.First,we establish that Cu S is an intrinsic type-Ⅱsuperconductor,correcting its long-standing classification as type-Ⅰ.Second,a complete set of anisotropic superconducting parameters is determined,including the critical fields,penetration depth and coherence length,which yield a Ginzburg–Landau parameterκ~1.5 and a moderate anisotropy ofγ~2.Our results indicate that this type-Ⅱsuperconductivity can be well-described by a conventional,weak-coupling,single-band s-wave pairing mechanism.This work fills a long-standing gap in the understanding of this archetypal superconductor.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1401800,2022YFA1604200,2022YFA1403900,2023YFA1406002,2024YFA1408301 and 2024YFA1408100)the National Natural Science Foun-dation of China(Grant Nos.12488201,12374066,12374154,12494593)+2 种基金Quantum Science and Technology-National Science and Technology Major Project(Grant No.2021ZD0301800)CAS Superconducting Research Project(Grant No.SCZX-0101)the Synergetic Extreme Condition User Facility(SECUF).
文摘The spatially-resolved laser-based high resolution angle resolved photoemission spectroscopy(ARPES)measurements have been performed on the optimally-doped HgBa_(2)Ca_(2)Cu_(3)O_(8+δ)(Hg1223)superconductor with a T_(c) of 133 K.Two distinct regions are identified on the cleaved surface:the single Fermi surface region where only one Fermi surface is observed,and the double Fermi surface region where two Fermi surface sheets are resolved coming from both the inner(IP)and outer(OP)CuO_(2) planes.The electronic structure and superconducting gap are measured on both of these two regions.In both cases,the observed electronic states are mainly concentrated near the nodal region.The momentum dependence of the superconducting gap deviates from the standard d-wave form.These results indicate that the surface electronic structure of Hg1223 behaves more like that of underdoped cuprates.
