Evidence for Jahn-Teller-driven metal-insulator transition in strained SrCrO3 from first-principles calculations

Abstract

Using density-functional theory (DFT) and its extension to DFT + U, we propose a possible scenario for a strain-induced metal-insulator transition which was reported recently in thin films of SrCrO3. The metal-insulator transition involves the emergence of a Jahn-Teller (JT) distortion similar to the case of the related rare-earth vanadates, which also exhibit a nominal d(2) occupation of the transition metal cation. Our calculations indicate that, for realistic values of the Hubbard U parameter, the unstrained system exhibits a C-type antiferromagnetically ordered ground state that is already rather close to a JT instability. However, the emergence of the JT distortion is disfavored by the large energetic overlap of the d(xz)/d(yz) band with the lower-lying d(xy) band. Tensile epitaxial strain lowers the energy of the d(xy) band relative to d(xz)/d(yz) and thus brings the system closer to the nominal filling of d(xy)(1)(d(xz)d(yz))(1). The JT distortion then lifts the degeneracy between the d(xz) and d(yz) orbitals and thus allows the material to open up a gap in the electronic band structure.