Interface enhanced superconductivity in FeSe/SrTiO 3 and the hidden nature

Abstract

. The superconductivity confined in a two-dimensional interface exhibits many exotic phenomena that have certain counterparts in layered cuprates and iron-based superconductors, and thus provides rare opportunities to reveal the mystery of high temperature superconductivity therein. By constructing and tailoring hybrid heterostructures such as FeSe/SrTiO 3 (FeSe/STO), interface-enhanced superconductivity arouses, and the substrate has been demonstrated to provide the phonons and enhance the strong electron– phonon coupling (EPC) withinmonolayer FeSe. More research and reporting systems uncover that the band-bending induced charge transfer at the interface could become a unified microscopic picture to design the andunconventionalsuperconductors,thecommoncharacteristicssuchasbandbendingandrigidbandshift are perceived in the FeSe/STO, LAO/STO and cuprate superconductors. This review may provide important information to inspect the mechanism of high- T c superconductivity from a di ff erent view. a unified microscopic picture on how the interface superconductivity is prompted remains puzzling. For this purpose, we not only review the experimental research including spectroscopic study of 1UC FeSe/STO, CuO 2 /Bi2212, but also reexamine the previous results of LAO/STO [31] and even cuprate superconductors, and aim to capture the common characteristics among them. The ef-fects of charge transfer and band alignment are discussed first in the four systems. Then the rigid band shift and EPC are examined in the 1UC FeSe/STO, cuprates and LAO/STO systems. The polar nature’s influence on LAO/STO and cuprate on the tilted band structure is highlighted. All dis-cussions include the similar token in cuprates and may provide more insights into understanding