RKKY Interaction in Spin Valve Structure with LaAlO<sub>3</sub> Spacer

RKKY interaction is an indirect interaction between localized magnetic moments mediated by conduction electrons. RKKY exchange interaction is mostly found in multilayer involving conductors as the non-magnetic spacer. However, recent experiment shows that LaAlO 3 spacer can intermediate long-range exchange interaction even though it is an insulator. Here we study the mechanism of RKKY interaction in LaAlO 3 . To study the effect of charge transfer, we perform a density functional theory (DFT) approach to obtain the band structure of LaAlO 3 with charge doping. Undoped LaAlO 3 has an indirect band gap around 3 eV with peak valence at R symmetry point and lowest conduction point at Γ point. We show that the conducting characteristic arises from Fermi energy shifts via charge doping. By adding charge doping, we show that LaAlO 3 can have conductor characteristics, in agreement with the charge transfer experiment on LaAlO 3 . The spin-polarized conduction electron is measurable as additional magnetization of the system. Furthermore, the conducting LaAlO 3 is able to mediate RKKY interaction in spin valve structure.