Electronic structure, phase stability, and magnetic properties of La1-xSrxCoO3 from first-principles full-potential calculations

In order to understand the role of hole doping on electronic structure, pha se stability and magnetic properties of LaCoO3 generalized-gradient-correct ed, relativistic first-principles full-potential density functional calcula tions have been performed for La1-xSrxCoO3 as a function of x, using the su percell approach as well as the virtual crystal approximation (VCA). It has been shown that the rhombohedral distortion is stabilizing the nonmagnetic (i.e., diamagnetic or paramagnetic) ground state in LaCoO3. Spin-polarized calculation on the hypothetical cubic perovskite phase of LaCoO3 shows tha t the ferromagnetic phase is lower in energy than the corresponding nonmagn etic phase. The analysis of the electronic structures show that a Peierls-J ahn-Teller-like instability arises in the ferromagnetic cubic phase and lea ds to the rhombohedral distortion in LaCoO3. The calculated magnetic moment for La1-xSrxCoO3 as a function of Sr substitution is found to be in very g ood agreement with recent neutron scattering measurements. We have successf ully explained the hole-doping induced, nonmagnetic-to-ferromagnetic transi tion as wen as the rhombohedral-to-cubic structural transition as a functio n of Sr substitution in La1-xSrxCoO3. Due to the failure of the density fun ctional theory to predict the semiconducting nature of LaCoO3, we are unabl e to explain the experimentally observed semiconductor-to-metal transition in LaCoO3 by Sr substitution. The origin of the ferromagnetism in La1-xSrxC oO3 has been explained through itinerant-band ferromagnetism. [S0163-1829(9 9)14047-5].