Spin and orbital ordering ofNd1−xSrxMnO3from LSDA+U calculations

Abstract

The electronic structures of ${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ with $x=\frac{1}{2}$ (high- and low-temperature phases) and $x=\frac{9}{16}$ were studied by using the rotation-invariant local spin density approximation (LSDA)+U formalism in the framework of the linear-muffin-tin orbital method in the atomic sphere approximation. The experimental magnetic structure is calculated to be the energetically lowest one among the different possible spin configurations for every compound under consideration. The orbital ordering is clearly demonstrated by the partial Mn $3d$ densities of states projected into a natural local basis for every ${\mathrm{MnO}}_{6}$ octahedron. The mechanism of antiferromagnetic and ferromagnetic couplings in these materials is discussed. Antiferromagnetic interlayer coupling at $x=\frac{9}{16}$ is attributed to a crystal structure with an anisotropic shorter interlayer distance.