关键词: 多层FeSe薄膜/
抗磁响应/
迈斯纳效应/
穿透深度
English Abstract
In-situ measurement of diamagnetic response of potassium-adsorbed multi-layer FeSe ultrathin films on SrTiO3(001) substrate
Chen Chuan-Ting1,Yao Gang1,
Duan Ming-Chao1,
Guan Dan-Dan1,
Li Yao-Yi1,2,
Zheng Hao1,2,
Wang Shi-Yong1,2,
Liu Can-Hua1,2,
Jia Jin-Feng1,2
1.Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China;
2.Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
Fund Project:Project supported by the National Basic Research Program of China (Grant Nos. 2016YFA0300403, 2016YFA0301003), the National Natural Science Foundation of China (Grant Nos. 11521404, 11574202, 11634009, 11655002, 11504230, U1632102), and the Funds of Shanghai Committee of Science and Technology, China (Grant Nos. 15JC1402300, 16DZ2260200).Received Date:12 August 2018
Accepted Date:14 September 2018
Published Online:20 November 2019
Abstract:A single-unit-cell layer FeSe ultrathin film grown on SrTiO3(001) substrate exhibits remarkable high-temperature superconductivity, which has aroused intensive research interest. Electron transfer from the substrate to the FeSe layer has been shown to play an indispensable role in enhancing the extraordinary superconductivity. With this idea, researchers have tried to search for new high-temperature superconducting material systems including K-adsorbed multi-layer FeSe ultrathin films, on which superconducting-like energy gaps have been observed with scanning tunneling spectroscopy and photoelectron spectroscopy. However, the high-temperature superconductivity of the multi-layer FeSe ultrathin films has not yet been confirmed by directly observing the zero resistance or Meissner effect. With a self-developed multi-functional scanning tunneling microscope (STM+), which enables not only usual STM functionality, but also in situ two-coil mutual inductance measurement, we successfully observe the diamagnetic response of a K-adsorbed multilayer FeSe ultrathin film grown on a SrTiO3(001) substrate, and thus determine its transition temperature to be 23.9 K. Moreover, we calculate the penetration depth of the film from the measured results and find that its low-temperature behavior exhibits a quadratic variation, which strongly indicates that the order parameter of the superconducting K-adsorbed multi-layer FeSe ultrathin film has an S± pairing symmetry.
Keywords: multi-layer FeSe ultrathin film/
diamagnetic response/
Meissner effect/
penetration depth
