Strain control of orbital polarization and correlated metal-insulator transition in La2CoMnO6 from first principles

Transition metal oxides show rich physical properties which are often influenced by external perturbation. Here, we report by first-principles calculations that strain enables switching of orbital occupancy of Co2+ in La2CoMnO6 and hence modifies electronic structure of La2CoMnO6. We find a metal-insulator transition in La2CoMnO6, which originates from the interplay between the strain induced lattice distortion and electron correlations. Such transition is understood upon the orbital polarization of Co2+, which takes on the d(xz/yz) character under compression, yet switches to the d(x2-y2) character under tension. The orbital switching presented should hold promise for many technological applications. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3662859]