Electronic structure and superconductivity of single-layer FeSe on Nb:SrTiO 3 /LaAlO 3 with varied tensile strain

作者：Zhichun Huang, Yan Pu, Haishui Xu, Dan Xu, Qi Song, Xin Lou, Chenhaoping Wen, Rui Peng, Donglai Feng · 发表于：2D Materials · 年份：2016 · DOI：10.1088/2053-1583/3/1/014005 · 被引用次数：20 · 研究领域：Iron-based superconductors research、Corporate Taxation and Avoidance、Physics of Superconductivity and Magnetism

To understand the high temperature superconductivity at 65 K in single-layer FeSe films grown on Nb:SrTiO 3 substrates, one crucial issue is to distinguish the effects of different interfacial interactions. In this paper, we decouple the effect of tensile strain with those of other interfacial interactions, and studying the corresponding electronic structure and superconducting gap behavior through in - situ angle resolved photoemission spectroscopy. By growing single-layer FeSe/Nb:SrTiO 3 /LaAlO 3 heterostructures with varied thicknesses of Nb:SrTiO 3 films, the tensile strain on FeSe is controlled from 0.6% to 3.7% while preserving other interfacial interactions as in single-layer FeSe grown on Nb:SrTiO 3 substrate. The electronic correlation strength is weakened with reduced tensile strain. The superconducting transition temperature ( T c ) is positively correlated with the tensile strain in single-layer FeSe/Nb:SrTiO 3 when the film morphology is well ordered. Remarkably, the T c remains 55 K in single-layer FeSe with negligible tensile strain. These results help to reveal the effect of tensile strain on the enhanced superconductivity in single-layer FeSe/Nb:SrTiO 3 .