Abstract
We have systematically investigated the influence of oxygen vacancy defects on the structural, electronic and magnetic properties of La1−xSrxMnO3 (x = 1/3) film by means of ab initio calculations using bare GGA as well as GGA+U formalism, in the latter of which, the on-site Coulombic repulsion parameter U for Mn 3d orbital has been determined by the linear response theory. It is revealed that the introduction of the vacancy defects causes prominent structural changes including the distortion of MnO6 octahedra and local structural deformation surrounding the oxygen vacancy. The GGA+U formalism yields a significantly larger structural change than the bare GGA method, surprisingly in contrast with the general notion that the inclusion of Hubbard U parameter exerts little influence on structural properties. The distortion of MnO6 octahedra leads to a corresponding variation in the hybridization between Mn 3d and O 2p, which gets strengthened if the Mn-O distance becomes smaller and vice versa. The magnetic moments of the Mn atoms located in three typical sites of the vacancy-containing supercell are all larger than those in the pristine system. We have characterized the O-vacancy defect as a hole-type defect that forms a negative charge center, attracting electrons.
Highlights
We have systematically investigated the influence of oxygen vacancy defects on the structural, electronic and magnetic properties of La1−xSrxMnO3 (x = 1/3) film by means of ab initio calculations using bare generalized gradient approximation (GGA) as well as GGA+U formalism, in the latter of which, the on-site Coulombic repulsion parameter U for Mn 3d orbital has been determined by the linear response theory
We have carried out the density functional theory (DFT)-based first principles calculations by using the generalized gradient approximation (GGA)+ U formalism to investigate the oxygen vacancy induced changes in the structural, electronic and magnetic properties LSMO system
We have carried out geometry optimization on the three supercell configurations shown in Fig. 1(a–c) using the GGA+ U formalism, the calculated energy difference between cases (a) and (b) in Fig. 1 is − 0.26 eV, and the energy difference between cases (a) and (c) in Fig. 1 is − 0.35 eV
Summary
The perovskite manganese oxides La1−xAxMnO3 (A = Ca, Ba, Sr) have attracted extensive attention thanks to their special electronic and magnetic properties as well as their potential applications[1,2,3] Among this group of the materials, La1−xSrxMnO3 (LSMO) exhibits exotic properties such as colossal magnetoresistance (CMR) and metal-insulator transition[4], which originate from the delicate coupling between charge, spin, and orbital and lattice degrees of freedom. The MnO6 octahedron is an important feature of the perovskite manganeseoxides, and the existence of an oxygen vacancy in an octahedron leads to a change in its structure via correlated deformation and rotation of neighboring octahedra. The formation energy of an oxygen vacancy with different charge state and the stability of different charge state are studied
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