Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO2H Films

Perovskite oxides ABO(3) continue to be a major focus in materials science. Of particular interest is the interplay between A and B 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, EuVO2H, which has alternating layers of EuH and VO2. A bulk EuVO2H behaves as a ferromagnetic insulator with a relatively high transition temperature (TC) of 10 K. However, the application of external pressure to the (EuVO2H)-V-II-O-III bulk or compressive strain from the substrate in the thin films induces ICT from the EuIIH layer to the (VO2)-O-III layer due to the extended empty V d(xy) orbital. The ICT phenomenon causes the VO2 layer to become conductive, leading to an increase in T-C that is dependent on the number of carriers in the d xy 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 Eu2+, 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.

Automated summary

In this study, an anionic approach was demonstrated to induce intersite charge transfer (ICT) in the oxyhydride perovskite EuVO2H, resulting in increased conductivity and transition temperature (T-C). Furthermore, a large perpendicular magnetic anisotropy was observed in thin films, providing new possibilities for materials with novel functions.