Fabrication of oxide/FeSe multilayer films using the PLD technique

Abstract

In this study, we demonstrate the successful fabrication of TiO2/FeSe/STO and TiO2/FeSe/LaAlO3 heterostructures using PLD. When the growth rates were sufficiently low, anatase TiO2, which has been reported to induce superconductivity in FeSe, could be grown epitaxially on FeSe. For TiO2/FeSe/STO, the FeSe/TiO2 interface was relatively clean, as confirmed by the observation of Laue fringes in FeSe(001) reflection. Although a thinner FeSe layer is expected to enhance Tc, our results instead suggest that deposition of TiO2 introduces additional disorder in FeSe. Most strikingly, superconductivity appeared when TiO2 was deposited on FeSe/LaAlO3, clearly demonstrating that the interaction between the top oxide layer and underlying FeSe can induce superconductivity. This work demonstrates the feasibility of fabricating FeSe/oxide superlattices by PLD, establishing a novel platform for the exploration of interfacial superconductivity in iron-based superconductors.