A simple technique is reported for fabricating the mesa structure on Bi2Sr2CaCu2O8+δ single crystal. In the patterning process, metal masks are used instead of photolithography and argon ion milling is applied to for...A simple technique is reported for fabricating the mesa structure on Bi2Sr2CaCu2O8+δ single crystal. In the patterning process, metal masks are used instead of photolithography and argon ion milling is applied to form the small mesa on the Bi2Sr2CaCu2O8+δ crystal surface. Real four-probe transport measurements are made on the mesa structure and typical c-axis current-voltage (I - V) characteristics of the intrinsic Josephson effect have been observed. The superconducting gap parameter can be extracted from the multi-branch structure in the I - V characteristics. Additionally, from the strong hysteresis in the I - V characteristics, the capacitance CJ of the unit intrinsic Josephson junction has been estimated to be 2.3pF, which is in good agreement with that evaluated from the geometric parameters of the unit junction between the two copper oxide layers.展开更多
We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the ...We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the transmission spectra using both THz time-domain spectroscopy and numerical simulation.The characteristic transmission peaks are found to be associated with the interaction of surface plasmon polaritons(SPPs)and localized surface plasmons(LSPs)for ring-shaped apertures.The effect of LSPs is less remarkable in the square apertures.For the superconducting NbN film,when the temperature is slightly lower than the critical transition temperature T_(c),the peak magnitude of SPP resonances is most prominent due to the non-monotonic temperature dependence of kinetic inductance.These results provide a new way to design compact and efficient THz devices.展开更多
For high-quality superconducting tunnel junctions(STJs),it is necessary to reduce leakage current as much as possible.We describe the fabrication of niobium STJs using the selective niobium(Nb)etching process and vari...For high-quality superconducting tunnel junctions(STJs),it is necessary to reduce leakage current as much as possible.We describe the fabrication of niobium STJs using the selective niobium(Nb)etching process and various ways to minimize the leakage current.The experiment shows that the leakage current mainly comes from shorts in the tunnel barrier layer rather than those around the junction edges.Through systematic analysis of the thin film stress,surface morphology and modified junction structures,we fabricate high-quality Nb STJs with a gap voltage of 2.8 mV and a leakage current at 1 mV as low as 8.1%and 0.023%at 4.2 K and 0.3 K,respectively.展开更多
基金the National Center for Research and Development on Superconductivity of Chinain part by the International Collaborative Research Project of Telecommunications Advancement Organization of Japan.
文摘A simple technique is reported for fabricating the mesa structure on Bi2Sr2CaCu2O8+δ single crystal. In the patterning process, metal masks are used instead of photolithography and argon ion milling is applied to form the small mesa on the Bi2Sr2CaCu2O8+δ crystal surface. Real four-probe transport measurements are made on the mesa structure and typical c-axis current-voltage (I - V) characteristics of the intrinsic Josephson effect have been observed. The superconducting gap parameter can be extracted from the multi-branch structure in the I - V characteristics. Additionally, from the strong hysteresis in the I - V characteristics, the capacitance CJ of the unit intrinsic Josephson junction has been estimated to be 2.3pF, which is in good agreement with that evaluated from the geometric parameters of the unit junction between the two copper oxide layers.
基金Supported by the National Basic Research Program of China(Nos 2011CBA00107,2011CBA00202)the National Natural Science Foundation of China under Grant Nos 61071009,61027008,11104110+1 种基金the Specialized Research Fund for Doctoral Program of Higher Education(20090091110040)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the transmission spectra using both THz time-domain spectroscopy and numerical simulation.The characteristic transmission peaks are found to be associated with the interaction of surface plasmon polaritons(SPPs)and localized surface plasmons(LSPs)for ring-shaped apertures.The effect of LSPs is less remarkable in the square apertures.For the superconducting NbN film,when the temperature is slightly lower than the critical transition temperature T_(c),the peak magnitude of SPP resonances is most prominent due to the non-monotonic temperature dependence of kinetic inductance.These results provide a new way to design compact and efficient THz devices.
基金by the National Natural Science Foundation of China under Grant Nos 2007CB310404 and 2011CBA00107the National Natural Science Foundation of China under Grant No 10874074the Doctoral Funds of the Ministry of Education of China under Grant No 20090091110039。
文摘For high-quality superconducting tunnel junctions(STJs),it is necessary to reduce leakage current as much as possible.We describe the fabrication of niobium STJs using the selective niobium(Nb)etching process and various ways to minimize the leakage current.The experiment shows that the leakage current mainly comes from shorts in the tunnel barrier layer rather than those around the junction edges.Through systematic analysis of the thin film stress,surface morphology and modified junction structures,we fabricate high-quality Nb STJs with a gap voltage of 2.8 mV and a leakage current at 1 mV as low as 8.1%and 0.023%at 4.2 K and 0.3 K,respectively.
