title: Ab initio electronic and magnetic structure in La(0.66)Sr(0.33)MnO(3): strain and correlation effects.
abstract: The effects of tetragonal strain on the electronic and magnetic properties of strontium-doped lanthanum manganite, La(2/3)Sr(1/3)MnO(3) (LSMO), are investigated by means of density-functional methods. As far as the structural properties are concerned, the comparison between theory and experiments for LSMO strained on the most commonly used substrates shows an overall good agreement: the slight overestimate (at most of 1-1.5%) for the equilibrium out-of-plane lattice constants points to possible defects in real samples. The inclusion of a Hubbard-like contribution on the Mn d states, according to the so-called 'LSDA+U' approach, is rather ineffective from the structural point of view, but much more important from the electronic and magnetic point of view. In particular, full half-metallicity, which is missed within a bare density-functional approach, is recovered within LSDA+U, in agreement with experiments. Moreover, the half-metallic behaviour, particularly relevant for spin-injection purposes, is independent of the chosen substrate and is achieved for all the considered in-plane lattice constants. More generally, strain effects are not seen to crucially affect the electronic structure: within the considered tetragonalization range, the minority gap is only slightly (i.e. by about 0.1-0.2 eV) affected by a tensile or compressive strain. Nevertheless, we show that the growth on a smaller in-plane lattice constant can stabilize the out-of-plane versus in-plane e(g) orbital and significantly change their relative occupancy. Since e(g) orbitals are key quantities for the double-exchange mechanism, strain effects are confirmed to be crucial for the resulting magnetic coupling.
authors.affiliation: Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, People's Republic of China. Department of Applied Physics, University of Science and Technology of Suzhou, Suzhou 215011, People's Republic of China.
authors.forename: Chunlan
authors.initials: C
authors.lastname: Ma
authors.forename: Zhongqin
authors.initials: Z
authors.lastname: Yang
authors.forename: Silvia
authors.initials: S
authors.lastname: Picozzi