Effects of chemical order and atomic relaxation on the electronic and magnetic properties of La2/3Sr1/3MnO3

We investigate the effects of Sr/La cation ordering/disordering and atomic relaxation on the electronic and magnetic properties of La2/3Sr1/3MnO3 (LSMO) by means of ab initio pseudopotential calculations. We consider a cation-ordered layered structure and a more homogeneously Sr-bulk-doped structure. Cation disordering and atomic relaxation both tend to push the LSMO system towards half-metallicity, increasing the minority-spin and spin-flip gaps. Lattice relaxation has a significant effect on the electronic density of states (DOS) of the layered LSMO and drastically reduces the initial differences found comparing the electronic properties of the perovskite structures with different dopant configurations. The trend with structural relaxation is understood in terms of an effective screening, due to the displacement of the O anions and La cations, of the local electric field produced by the ordered Sr dopants.