Seminar: Superconductivity on one-unit-cell scale

Superconductivity on one-unit-cell scale

Prof. Xucun Ma

Department of Physics, Tsinghua University, 100084 Beijing, China

Abstract:
Heterostructure based interface engineering has been proved an effective method for finding new superconducting systems and raising superconducting transition temperature. Recently discovered high temperature superconductivity in one unit-cell (UC) FeSe films on SrTiO3 substrate grown by molecular beam epitaxy has attracted intensive attention. In sharp contrast to FeSe films on graphene where a 2.2 meV superconducting gap is observed on thick (~ 16.5 nm) films and no superconducting gap on 1-UC FeSe down to 2.3 K, 1-UC FeSe films on STO substrate exhibit unexpected large superconducting gaps of 15-20 meV. Interestingly, the anomalously large superconducting gap is only found in the first UC FeSe but not on 2-UC or thicker layers, indicating that interface plays a crucial role in the enhanced superconductivity in 1-UC FeSe films on STO substrate. In this talk, a comprehensive study of 1- UC FeSe films by in situ scanning tunneling microscopy/spectroscopy and angle-resolved photoemission spectroscopy and ex situ transport measurements will be presented to discuss the possible superconducting mechanism in this well-defined heterostructure.
References: 
[1] Q. Y. Wang et al., Chin. Phys. Lett. 29, 037402 (2012). 
[2] W. H. Zhang et al., Chin. Phys. Lett. 31, 017401 (2014). 
[3] Y. F. Lv et al., arXiv: 1508.07460 (2015).
[4] The work was carried out in collaboration with Qikun Xue, Lili Wang, Canli Song, Yayu Wang, Ke He, Xi Chen, Shuaihua Ji, Xiangjiang Zhou, Feng Liu, and Shengbai Zhang.
 

Time: 3 pm, Friday, October 16, 2015
Place: Room 423, teaching building number 12, Yuquan Campus

个人简介：
马旭村，清华大学物理系教授，国家杰出青年科学基金获得者。1992年北京大学本科毕业，1997年获中科院盐湖所硕士学位，2000年获中科院物理所博士学位。2000年至2002年在德国 马普研究学会微结构物理研究所做博士后研究，2003年加入中科院物理所表面物理国家重点实验室工作，2013年加入清华大学物理系，任教授，博士生导师。马旭村教授主要研究低维结构的控制生长/量子效应和表面吸附/催化研究，曾获得“求是杰出科学家集体奖”、“陈嘉庚数理科学奖”、“中国青年女科学家奖”等。