Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/spectroscopy, we clearly ...Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/spectroscopy, we clearly reveal the spatial-dependence or inhomogeneity of the superconducting gap structure of Bi2Sr2CaCu2O8＋δ （Bi2212） and YBa2Cu3O7-x （YBCO） along their c-axes on a scale shorter than the interlayer spacing. By tunneling into the （100） plane of a Bi2212 single crystal and a YBCO film, we observe both U-shaped tunneling spectra with extended fiat zero-conductance bottoms, and V-shaped gap structures, in different regions of each sample. On the YBCO film, tunneling into a （110） surface only reveals a U-shaped gap without any zero-bias peak. Our analysis suggests that the U-shaped gap is likely a nodeless superconducting gap. The V-shaped gap has a very small amplitude, and is likely proximity-induced by regions having the larger U-shaped gap.展开更多
A nodeless variable element method with the fluxbased formulation is developed to analyze two-dimensional thermal-structural problems. The nodeless variable formula- tion provides accurate temperature distributions to...A nodeless variable element method with the fluxbased formulation is developed to analyze two-dimensional thermal-structural problems. The nodeless variable formula- tion provides accurate temperature distributions to yield more accurate thermal stress solutions. The flux-based formulation is used to reduce the complexity in deriving the finite element equations as compared to the conventional finite element method. The solution accuracy is further improved by implementing an adaptive meshing technique to generate finite element meshes that can adapt and move along with the transient solution behavior. A version of a nearly optimal element size determination is proposed to provide high convergence rate of the predicted solutions. The combined procedure is evaluated by solving several thermal, structural, and thermal stress problems.展开更多
We experimentally demonstrate low-latency,high-capacity,and long-haul coherent transmission,recirculated through a self-fabricated,low-loss,and long-span 20 km nested antiresonant nodeless fiber(NANF)in the C-band.By ...We experimentally demonstrate low-latency,high-capacity,and long-haul coherent transmission,recirculated through a self-fabricated,low-loss,and long-span 20 km nested antiresonant nodeless fiber(NANF)in the C-band.By leveraging wavelength division multiplexing(WDM),polarization multiplexing,probabilistic amplitude shaping technology,and low-complexity receiver-side digital signal processing(DSP),we achieve a record-breaking transmission capacity of 16.763 Tb/s over 1000 km for the first time,to the best of our knowledge.This achievement represents a significant step forward in highcapacity and long-haul optical communication based on NANF.展开更多
The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate ...The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate directly the superconducting CuO2 layers. Here, by growing CuO2 monolayer films on Bi2Sr2CaCu2O8＋δ substrates, we identify two distinct and spatially separated energy gaps centered at the Fermi energy, a smaller U-like gap and a larger V-like gap on the films, and study their interactions with alien atoms by low-temperature scanning tunneling microscopy. The newly discovered U-like gap exhibits strong phase coherence and is immune to scattering by K, Cs and Ag atoms, suggesting its nature as a nodeless superconducting gap in the CuO2 layers, whereas the V-like gap agrees with the well-known pseudogap state in the underdoped regime. Our results support an s-wave superconductivity in Bi2Sr2CaCu2O8＋δ, which, we pro- pose, originates from the modulation-doping resultant twodimensional hole liquid confined in the CuO2 layers.展开更多
Low-temperature specific heat was measured on the BaFe_(1.9)Ni_(0.1)As_(2) single crystals with critical transition temperature Tc=20.1 K.A clear specific heat jump with the valueΔC/T|_(Tc)≈23 mJ/mol K^(2) was obser...Low-temperature specific heat was measured on the BaFe_(1.9)Ni_(0.1)As_(2) single crystals with critical transition temperature Tc=20.1 K.A clear specific heat jump with the valueΔC/T|_(Tc)≈23 mJ/mol K^(2) was observed.In addition,a roughly linear magnetic field dependence of the electronic specific heat coefficientΔγ(H)was found in the zero-temperature limit,suggesting that at least one Fermi pocket,probably the hole derivative one,was fully gapped with a small anisotropy in the present sample.A slight curvature of the curveΔγ(H)may suggest a complex gap structure(anisotropic gap or nodes)at other Fermi surfaces.展开更多
基金Supported by the National Natural Science Foundation of Chinathe National Key Research and Development Program of China under Grant No 2016YFA0300203
文摘Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/spectroscopy, we clearly reveal the spatial-dependence or inhomogeneity of the superconducting gap structure of Bi2Sr2CaCu2O8＋δ （Bi2212） and YBa2Cu3O7-x （YBCO） along their c-axes on a scale shorter than the interlayer spacing. By tunneling into the （100） plane of a Bi2212 single crystal and a YBCO film, we observe both U-shaped tunneling spectra with extended fiat zero-conductance bottoms, and V-shaped gap structures, in different regions of each sample. On the YBCO film, tunneling into a （110） surface only reveals a U-shaped gap without any zero-bias peak. Our analysis suggests that the U-shaped gap is likely a nodeless superconducting gap. The V-shaped gap has a very small amplitude, and is likely proximity-induced by regions having the larger U-shaped gap.
文摘A nodeless variable element method with the fluxbased formulation is developed to analyze two-dimensional thermal-structural problems. The nodeless variable formula- tion provides accurate temperature distributions to yield more accurate thermal stress solutions. The flux-based formulation is used to reduce the complexity in deriving the finite element equations as compared to the conventional finite element method. The solution accuracy is further improved by implementing an adaptive meshing technique to generate finite element meshes that can adapt and move along with the transient solution behavior. A version of a nearly optimal element size determination is proposed to provide high convergence rate of the predicted solutions. The combined procedure is evaluated by solving several thermal, structural, and thermal stress problems.
基金supported by the Shenzhen Science and Technology Program(No.RCBS20231211090602010)the Major Key Project of PCL。
文摘We experimentally demonstrate low-latency,high-capacity,and long-haul coherent transmission,recirculated through a self-fabricated,low-loss,and long-span 20 km nested antiresonant nodeless fiber(NANF)in the C-band.By leveraging wavelength division multiplexing(WDM),polarization multiplexing,probabilistic amplitude shaping technology,and low-complexity receiver-side digital signal processing(DSP),we achieve a record-breaking transmission capacity of 16.763 Tb/s over 1000 km for the first time,to the best of our knowledge.This achievement represents a significant step forward in highcapacity and long-haul optical communication based on NANF.
基金Acknowledgments The work was financially supported by the National Natural Science Foundation, Ministry of Science and Technology and Ministry of Education of China. The work at Brookhaven National Laboratory was supported by the Office of Basic Energy Sciences, US Department of Energy, under Contract No. DE- SC00112704.
文摘The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate directly the superconducting CuO2 layers. Here, by growing CuO2 monolayer films on Bi2Sr2CaCu2O8＋δ substrates, we identify two distinct and spatially separated energy gaps centered at the Fermi energy, a smaller U-like gap and a larger V-like gap on the films, and study their interactions with alien atoms by low-temperature scanning tunneling microscopy. The newly discovered U-like gap exhibits strong phase coherence and is immune to scattering by K, Cs and Ag atoms, suggesting its nature as a nodeless superconducting gap in the CuO2 layers, whereas the V-like gap agrees with the well-known pseudogap state in the underdoped regime. Our results support an s-wave superconductivity in Bi2Sr2CaCu2O8＋δ, which, we pro- pose, originates from the modulation-doping resultant twodimensional hole liquid confined in the CuO2 layers.
基金supported by the National Natural Science Foundation of China(Grant Nos.10221002/A0402 and 10774170/A0402)the National Basic Research Program of China(Grant Nos.2006CB601000,2006CB921107,and 2006CB921802)the Chinese Academy of Sciences(ITSNEM)
文摘Low-temperature specific heat was measured on the BaFe_(1.9)Ni_(0.1)As_(2) single crystals with critical transition temperature Tc=20.1 K.A clear specific heat jump with the valueΔC/T|_(Tc)≈23 mJ/mol K^(2) was observed.In addition,a roughly linear magnetic field dependence of the electronic specific heat coefficientΔγ(H)was found in the zero-temperature limit,suggesting that at least one Fermi pocket,probably the hole derivative one,was fully gapped with a small anisotropy in the present sample.A slight curvature of the curveΔγ(H)may suggest a complex gap structure(anisotropic gap or nodes)at other Fermi surfaces.
