关键词: FeSe/MgO界面/
界面超导增强/
扫描隧道显微镜/
扫描透射电子显微镜
English Abstract
Interface enhanced superconductivity in monolayer FeSe film on oxide substrate
Ding Cui1,Liu Chong1,
Zhang Qing-Hua2,
Gong Guan-Ming1,
Wang Heng1,
Liu Xiao-Zhi2,
Meng Fan-Qi2,
Yang Hao-Hao1,
Wu Rui1,
Song Can-Li1,3,
Li Wei1,3,
He Ke1,3,
Ma Xu-Cun1,3,
Gu Lin2,3,
Wang Li-Li1,3,
Xue Qi-Kun1,3
1.State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China;
2.Beijing National Laboratory for Condensed Matter Physics, Laboratory for Advanced Materials and Electron Microscopy, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
3.Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 11574174, 11774193, 11790311, 51522212, 51421002, 51672307), the National Basic Research Program of China (Grant Nos. 2015CB921000, 2014CB921002), and the Strategic Priority Research Program of the Chinese Academy of Sciences, China (Grant No. XDB07030200).Received Date:10 September 2018
Accepted Date:21 September 2018
Published Online:20 October 2019
Abstract:We report on the observation of a superconducting gap of about 14-15 meV, significantly enlarged compared with the value of 2.2 meV for bulk FeSe, in monolayer FeSe film interfaced with MgO epitaxial on SrTiO3(001) substrate by using the scanning tunneling microscopy. While the MgO exhibits the same work function as SrTiO3 substrate, the gap magnitude is in coincidence with that of surface K-doped two-unit-cell FeSe film on SrTiO3(001), suggesting that the interface enhanced superconductivity might be attributed to cooperation of interface charge transfer driven by band bending with interface electron-phonon coupling as discovered at FeSe/TiO2 interfaces. On the other hand, the observation of such an enlarged superconducting gap, complementary to our previous transport observation of an onset superconducting transition temperature of 18 K in monolayer FeSe film on a bulk MgO substrate, implies that FeSe/MgO interface is likely to be a new interface high-temperature superconducting system, providing a new platform for investigating the mechanism of interface hightemperature superconductivity.
Keywords: FeSe/MgO/
interface enhanced superconductivity/
scanning tunneling microscopy/
scanning transmission electron microscopy
