title: Orbital Delocalization and Enhancement of Magnetic Interactions in Perovskite Oxyhydrides.
abstract: Recent experiments showed that some perovskite oxyhydrides have surprisingly high magnetic-transition temperature. In order to unveil the origin of this interesting phenomenon, we investigate the magnetism in SrCrO2H and SrVO2H on the basis of first-principles calculations and Monte Carlo simulations. Our work indicates that the Cr-O-Cr superexchange interaction in SrCrO2H is unexpectedly strong. Different from the previous explanation in terms of the H(-) ion substitution induced increase of the Cr-O-Cr bond angle, we reveal instead that this is mainly because the 3d orbitals in perovskite oxyhydrides becomes more delocalized since H(-) ions have weaker electronegativity and less electrons than O(2-) ions. The delocalized 3d orbitals result in stronger Cr-O interactions and enhance the magnetic-transition temperature. This novel mechanism is also applicable to the case of SrVO2H. Furthermore, we predict that SrFeO2H will have unprecedented high Neel temperature because of the extraordinarily strong Fe-H-Fe σ-type interactions. Our work suggests the anion substitution can be used to effectively manipulate the magnetic properties of perovskite compounds.
authors.affiliation: Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Fudan University, Shanghai 200433, P.R. China.
authors.forename: Kai
authors.initials: K
authors.lastname: Liu
authors.affiliation: Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Fudan University, Shanghai 200433, P.R. China.
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Fudan University, Shanghai 200433, P.R. China.
authors.forename: Xingao
authors.initials: X
authors.lastname: Gong
authors.affiliation: Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Fudan University, Shanghai 200433, P.R. China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Xiang