Ground-state and excited-state properties of LaMnO3 from full-potential calculations

The ground-state and excited-state properties of the perovskite LaMn03, the mother material of colossal magnetoresistance manganites, are calculated based on the generalized-gradient-corrected relativistic full- potential method. The electronic structure, magnetism, and energetics of various spin configurations for LaMnO3 in the ideal cubic perovskite structure and the experimentally observed distorted orthorhombic structure are obtained. The excited-state properties such as the optical, magneto-optical x-ray photoemission bremsstrahlung isochromat, and x-ray absorption near-edge structure spectra are calculated and found to be in excellent agreement with available experimental results. Consistent with earlier observations the insulating behavior can be obtained only when we take into account the structural distortions and the correct antiferro magnetic ordering in the calculations. The present results suggest that the correlation effect is not significant in LaMnO3 and the presence of ferromagnetic coupling within the ab plane as well as the antiferromagnetic coupling perpendicular too this plane can be explained through the itinerant band picture. Our calculations show that the Mn 3d eg-like electrons are present in the whole valence-band region. We have calculated the hyperfine field parameters for the A-type antiferromagnetic and the ferromagnetic phases of LaMnO3 and compared the findings with the available experimental results. The role of the orthorhombic distortion on electronic structure, magnetism, and optical anisotropy is analyzed. (author)