Fe Atomic Monolayer in a Coherent Interface: Electrostatic Potential-Induced Segregation and Interfacial Magnetism.

Abstract

Interfaces and boundaries often trap various impurities so that they play a crucial role in tailoring the mechanical and physical properties of materials and devices. Due to the perfect lattice matching, impurity segregation at coherent interfaces and the corresponding effects on material properties have rarely been reported. In this study, we demonstrate the segregation of an Fe atomic monolayer in a Sr₃MgSi₂O₈/SrTiO₃ coherent heterointerface and the resulting interfacial magnetism by combining aberration-corrected transmission electron microscopy, magnetic force microscopy, and first-principles calculations. It is revealed that the segregated Fe atomic monolayer consists of Fe³⁺ ions and exhibits ferromagnetism. The Sr₃MgSi₂O₈/SrTiO₃ coherent interface shows no strain concentration with the Fe segregation driven by the minimization of interfacial electrostatic potential. These findings could deepen our understanding of impurity segregation at coherent interfaces. The as-received interfacial magnetism at the coherent interface is expected to play important roles in applications of future spintronic nanodevices.