Electron Leakage and Double-Exchange Ferromagnetism at the Interface between a Metal and an Antiferromagnetic Insulator:CaRuO3/CaMnO3

Abstract

Density-functional electronic structure studies of a prototype interface between a paramagnetic metal and an antiferromagnetic (AFM) insulator (${\mathrm{CaRuO}}_3/{\mathrm{CaMnO}}_3$) reveal the exponential leakage of the metallic electrons into the insulator side. The leaked electrons in turn control the magnetism at the interface via the ferromagnetic (FM) Anderson-Hasegawa double exchange, which competes with the AFM superexchange of the bulk ${\mathrm{CaMnO}}_3$. The competition produces a FM interfacial ${\mathrm{CaMnO}}_3$ layer (possibly canted); but beyond this layer, the electron penetration is insufficient to alter the bulk magnetism.