High temperature superconductivity at FeSe/LaFeO3 interface
Yuanhe Song, Zheng Chen, Qinghua Zhang, Haichao Xu, Xia Lou, Xiaoyang Chen, Xiaofeng Xu, Xuetao Zhu, Ran Tao, Tianlun Yu, Hao Ru, Yihua Wang, Tong Zhang, Jiandong Guo, Lin Gu, Yanwu Xie, Rui Peng, Donglai Feng
Abstract
Abstract Enormous enhancement of superconducting pairing temperature ( T g ) to 65 K in FeSe/SrTiO 3 has made it a spotlight. Despite the effort of interfacial engineering, FeSe interfaced with TiO x remains the unique case in hosting high T g , hindering a decisive understanding on the general mechanism and ways to further improving T g . Here we constructed a new high- T g interface, single-layer FeSe interfaced with FeO x -terminated LaFeO 3 . Large superconducting gap and diamagnetic response evidence that the superconducting pairing can emerge near 80 K, highest amongst all-known interfacial superconductors. Combining various techniques, we reveal interfacial charge transfer and strong interfacial electron-phonon coupling (EPC) in FeSe/LaFeO 3 , showing that the cooperative pairing mechanism works beyond FeSe-TiO x . Intriguingly, the stronger interfacial EPC than that in FeSe/SrTiO 3 is likely induced by the stronger interfacial bonding in FeSe/LaFeO 3 , and can explain the higher T g according to recent theoretical calculations, pointing out a workable route in designing new interfaces to achieve higher T g .