Observation of robust edge superconductivity in Fe(Se,Te) under strong magnetic perturbation

Da Jiang; Yinping Pan; Shiyuan Wang; Yishi Lin; Connor M Holland; John R Kirtley; Xianhui Chen; Jun Zhao; Lei Chen; Shaoyu Yin; Yihua Wang

doi:10.1016/j.scib.2020.10.006

Observation of robust edge superconductivity in Fe(Se,Te) under strong magnetic perturbation

Sci Bull (Beijing). 2021 Mar 15;66(5):425-432. doi: 10.1016/j.scib.2020.10.006. Epub 2020 Oct 15.

Authors

Da Jiang¹, Yinping Pan², Shiyuan Wang², Yishi Lin², Connor M Holland³, John R Kirtley³, Xianhui Chen⁴, Jun Zhao², Lei Chen⁵, Shaoyu Yin⁶, Yihua Wang⁷

Affiliations

¹ Shanghai Institute of Microsystem and Information Technology, Shanghai 200050, China. Electronic address: jiangda@mail.sim.ac.cn.
² State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
³ Department of Physics, Stanford University, Stanford, CA 94305, USA.
⁴ Department of Physics, University of Science and Technology of China, Hefei 230026, China.
⁵ Shanghai Institute of Microsystem and Information Technology, Shanghai 200050, China.
⁶ Institute for Theoretical Physics and Cosmology, Zhejiang University of Technology, Hangzhou 310023, China; State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China. Electronic address: syyin@zjut.edu.cn.
⁷ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China. Electronic address: wangyhv@fudan.edu.cn.

PMID: 36654179
DOI: 10.1016/j.scib.2020.10.006

Abstract

The iron-chalcogenide high temperature superconductor Fe(Se,Te) (FST) has been reported to exhibit complex magnetic ordering and nontrivial band topology which may lead to novel superconducting phenomena. However, the recent studies have so far been largely concentrated on its band and spin structures while its mesoscopic electronic and magnetic response, crucial for future device applications, has not been explored experimentally. Here, we used scanning superconducting quantum interference device microscopy for its sensitivity to both local diamagnetic susceptibility and current distribution in order to image the superfluid density and supercurrent in FST. We found that in FST with 10% interstitial Fe, whose magnetic structure was heavily disrupted, bulk superconductivity was significantly suppressed whereas edge still preserved strong superconducting diamagnetism. The edge dominantly carried supercurrent despite of a very long magnetic penetration depth. The temperature dependences of the superfluid density and supercurrent distribution were distinctively different between the edge and the bulk. Our Heisenberg modeling showed that magnetic dopants stabilize anti-ferromagnetic spin correlation along the edge, which may contribute towards its robust superconductivity. Our observations hold implication for FST as potential platforms for topological quantum computation and superconducting spintronics.

Keywords: Anti-ferromagnetic spin correlation; Edge superconductivity; Iron-chalcogenide superconductors; Magnetic perturbation; Scanning SQUID microscopy.