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 $\mathrm{DFT}+U$, we propose a possible scenario for a strain-induced metal-insulator transition which was reported recently in thin films of $\mathrm{Sr}\mathrm{Cr}{\mathrm{O}}_{3}$. 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.