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

We present a potential explanation for the strain-induced metal-insulator transition that has recently been observed in thin films of SrCrO₃ using density-functional theory (DFT) and its extension to DFT+U. Our calculations show that the unstrained system exhibits a C-type antiferromagnetically ordered ground state, which is near to a Jahn-Teller instability, given realistic values of the Hubbard U parameter. However, the significant energy overlap between the higher-lying d_xy band and the d_xz/d_yz band works against the JT distortion's. When epitaxially strained, this overlap is reduced by the lowering of the d_xyband relative to d_xz/d_yz as the system gets closer to the nominal integer filling. The degeneracy between the d_xz and d_yz orbitals is subsequently lifted by the JT distortion, opening a gap in the electronic band structure.