程光磊博士
美国Pittsburgh大学 研究助理教授
报告时间：2015年7月 2日(周四)上午10：00
报告地点：唐仲英楼A-213
摘要：The strongly enhanced electron-electron correlations at oxide interfaces have given rise to a set of novel electronic phases not present in the bulk. The LaAlO3/SrTiO3 (LAO/STO) interface is a prime example that possesses superconductivity, spin-orbit interaction, magnetism and metal-insulator transition. The superconductivity in STO has long thought to be unconventional since it has the highest known transition temperature/carrier density (Tc/n), a quantity suggesting possible strong electron pairing, as well as a phase diagram like high-Tc superconductors. Despite sustained interest in the superconducting properties of STO, direct experimental insight into the nature of electron pairing in this superconducting semiconductor has remained elusive. Here I will present our investigation of electron pairing through superconducting single-electron transistors (SSET) created by the conductive atomic force microscopy (c-AFM) at the LAO/STO interface. Essentially, we have found the electron pairing are robust at magnetic fields and temperatures well outside of the range at which superconductivity is observed. These experimental findings are qualitatively consistent with a real-space strong pairing mechanism, providing parameters for an attractive-U Hubbard model description [1].In addition, I will talk about related experiments on Andreev bound state, Fabry-Perot resonator and quantum point contacts.
[1] Guanglei Cheng et al., “Electron pairing without superconductivity”. Nature 521, 196-199 (2015).