Octahedral rotation induced spin state and metal–insulator transition in LaCoO[formula omitted] films

Abstract

The discussions over the origins of the magnetic and insulating properties in LaCoO3 films has continued unabated even now. We investigate the energy of natural low spin, homogeneous intermediate spin, and mixed spin configurations using first principle calculations, taking into account various distortions in bulk and films. The spin state transition can be controlled by rhombohedral distortion and octahedral rotations in films bulk. The octahedral rotation reserved in the films bulk, and it can also induce the breathing distortion or the Jahn–Teller distortion when increase the mismatch ratio. The breathing distortion or the Jahn–Teller distortion change the electronic structure from a metal to semiconductor. The octahedral rotations can be a efficient regulatory to control electronic structure and spin states. The constrain of mixed spin configuration (IS:LS=1:2) potentially cause a charge disproportionation, resulting in a quasi-breathing distortion similar to magnetoelastic effect.