We report high transition temperature superconductivity in one unit-cell(UC)thick FeSe films grown on a Seetched SrTiO_(3)(001)substrate by molecular beam epitaxy(MBE).A superconducting gap as large as 20 meV and the ...We report high transition temperature superconductivity in one unit-cell(UC)thick FeSe films grown on a Seetched SrTiO_(3)(001)substrate by molecular beam epitaxy(MBE).A superconducting gap as large as 20 meV and the magnetic field induced vortex state revealed by in situ scanning tunneling microscopy(STM)suggest that the superconductivity of the 1 UC FeSe films could occur around 77K.The control transport measurement shows that the onset superconductivity temperature is well above 50K.Our work not only demonstrates a powerful way for finding new superconductors and for raising Tc,but also provides a well-defined platform for systematic studies of the mechanism of unconventional superconductivity by using different superconducting materials and substrates.展开更多
Atomically fiat thin films of topological semimetal Na3Bi are grown on double-layer graphene formed on 6H SiC（0001） substrates by molecular beam epitaxy. By combined techniques of molecular beam epitaxy, scanning tu...Atomically fiat thin films of topological semimetal Na3Bi are grown on double-layer graphene formed on 6H SiC（0001） substrates by molecular beam epitaxy. By combined techniques of molecular beam epitaxy, scanning tunneling microscopy and angle resolved photoelectron spectroscopy, the growth conditions for NaaBi thin films on double-layer graphene are successfully established. The band structure of NaaBi grown on graphene is mapped along Г-M and Г-K; directions. Furthermore, the energy band of Na3Bi at higher energy is uncovered by doping Cs atoms on the surface.展开更多
通过对超高压直流输电模型研究,发现低压限流控制器(voltage dependent current order limiter,VDCOL)的静态恢复关系和获取补偿电压的方法对连续换相失败有较大的影响,改变VDCOL所采用数学模型的斜率和获取补偿电压方法有利于减少连续...通过对超高压直流输电模型研究,发现低压限流控制器(voltage dependent current order limiter,VDCOL)的静态恢复关系和获取补偿电压的方法对连续换相失败有较大的影响,改变VDCOL所采用数学模型的斜率和获取补偿电压方法有利于减少连续换相失败次数。为降低直流输电系统发生连续换相失败的可能性,提出了基于虚拟电阻电流限制控制方法的精确变斜率低压限流控制器的设计方案。使用PSCAD中的CIGRE标准测试模型进行相关仿真,最后通过对相关数据的分析,验证了所提出的控制方法在单相和三相接地故障中对抑制连续换相失败的有效性。展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10721404 and 11134008the National Basic Research Program of China under Grant No 2009CB929400.
文摘We report high transition temperature superconductivity in one unit-cell(UC)thick FeSe films grown on a Seetched SrTiO_(3)(001)substrate by molecular beam epitaxy(MBE).A superconducting gap as large as 20 meV and the magnetic field induced vortex state revealed by in situ scanning tunneling microscopy(STM)suggest that the superconductivity of the 1 UC FeSe films could occur around 77K.The control transport measurement shows that the onset superconductivity temperature is well above 50K.Our work not only demonstrates a powerful way for finding new superconductors and for raising Tc,but also provides a well-defined platform for systematic studies of the mechanism of unconventional superconductivity by using different superconducting materials and substrates.
基金教育部考试中心—英国文化教育协会2020年英语测评科研课题之重点课题“An Empirical Study into the Validity of a CSE-based Placement test in China's Transnational Higher Education”(考协[2020]263号)。
基金Supported by the National Natural Science Foundation of China under Grant Nos 11025419 and 50831006, and the National Basic Research Program of China under Grant No 2011CB921904.
文摘Atomically fiat thin films of topological semimetal Na3Bi are grown on double-layer graphene formed on 6H SiC（0001） substrates by molecular beam epitaxy. By combined techniques of molecular beam epitaxy, scanning tunneling microscopy and angle resolved photoelectron spectroscopy, the growth conditions for NaaBi thin films on double-layer graphene are successfully established. The band structure of NaaBi grown on graphene is mapped along Г-M and Г-K; directions. Furthermore, the energy band of Na3Bi at higher energy is uncovered by doping Cs atoms on the surface.
文摘通过对超高压直流输电模型研究,发现低压限流控制器(voltage dependent current order limiter,VDCOL)的静态恢复关系和获取补偿电压的方法对连续换相失败有较大的影响,改变VDCOL所采用数学模型的斜率和获取补偿电压方法有利于减少连续换相失败次数。为降低直流输电系统发生连续换相失败的可能性,提出了基于虚拟电阻电流限制控制方法的精确变斜率低压限流控制器的设计方案。使用PSCAD中的CIGRE标准测试模型进行相关仿真,最后通过对相关数据的分析,验证了所提出的控制方法在单相和三相接地故障中对抑制连续换相失败的有效性。
