Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVOH Films.

Perovskite oxides O continue to be a major focus in materials science. Of particular interest is the interplay between and cations as exemplified by intersite charge transfer (ICT), which causes novel phenomena including negative thermal expansion and metal-insulator transition. However, the ICT properties were achieved and optimized by cationic substitution or ordering. Here we demonstrate an anionic approach to induce ICT using an oxyhydride perovskite, EuVOH, which has alternating layers of EuH and VO. A bulk EuVOH behaves as a ferromagnetic insulator with a relatively high transition temperature () of 10 K. However, the application of external pressure to the EuVOH bulk or compressive strain from the substrate in the thin films induces ICT from the EuH layer to the VO layer due to the extended empty V d orbital. The ICT phenomenon causes the VO layer to become conductive, leading to an increase in that is dependent on the number of carriers in the d orbitals (up to a factor of 4 for 10 nm thin films). In addition, a large perpendicular magnetic anisotropy appears with the ICT for the films of <100 nm, which is unprecedented in materials with orbital-free Eu, opening new perspectives for applications. The present results provide opportunities for the acquisition of novel functions by alternating transition metal/rare earth layers with heteroanions.