Large Perpendicular Magnetic Anisotropy Induced by an Intersite Charge Transfer in Strained EuVO<sub>2</sub>H Films
Morito Namba, Hiroshi Takatsu, Riho Mikita, Yao Sijia, Kantaro Murayama, Hao‐Bo Li, Ryo Terada, Cédric Tassel, Hiroki Ubukata, Masayuki Ochi, R. Sáez-Puche, Elias Palacios Latasa, Naoki Ishimatsu, Daisuke Shiga, Hiroshi Kumigashira, Katsuki Kinjo, Shunsaku Kitagawa, Kenji Ishida, Takahito Terashima, Koji Fujita, Takeaki Mashiko, Keiichi Yanagisawa, Koji Kimoto, Hiroshi Kageyama
Abstract
Perovskite oxides AB O 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, EuVO 2 H, which has alternating layers of EuH and VO 2 . A bulk EuVO 2 H behaves as a ferromagnetic insulator with a relatively high transition temperature ( T C ) of 10 K. However, the application of external pressure to the Eu II V III O 2 H bulk or compressive strain from the substrate in the thin films induces ICT from the Eu II H layer to the V III O 2 layer due to the extended empty V d xy orbital. The ICT phenomenon causes the VO 2 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 Eu 2+, 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.