Orbital ordering in Fe1-xMnx V2 O4: A first-principles study

Abstract

Long-range orbital order has been investigated in Fe1-xMnxV2O4 as a function of doping (x) using first-principles density functional theory calculations including the effects of Coulomb correlation and spin-orbit interaction within GGA+U and GGA+U+SO approximations. Through a detailed analysis of corresponding Wannier orbital projections of the vanadium d bands, we have clearly established that for x≤0.6, the orbital order at V sites consists of a linear superposition of dxz and dyz orbitals of the type dxz±dyz. Within each ab plane a ferro-orbital ordering of either dxz+dyz or dxz-dyz is observed which alternates in successive ab planes along the c direction. On the contrary, for x>0.6, it is the dxz or dyz orbital that orders at V sites in successive ab planes along c direction (so-called A-type ordering). At Fe sites, we observe an orbital ordering of dx2-y2 orbitals for x≤0.6 and dz2 orbitals for x>0.6. The effect of spin-orbit interaction on orbital ordering is found to be not significant in the entire range of doping studied. © 2016 American Physical Society.