Calculations of electronic structure and hyperfine parameters in oxides
authors J. N. Gonçalves
supervisors V. S. Amaral, J. G. Correia
thesis type Master
nationality International
author keywords Magnetic oxides, manganites, hyperfine properties, computational method, ab initio, perturbed angular correlation
abstract First principles calculations of electronic structure are done on perovskite manganese based oxides LaMnO 3 and CaMnO 3 to obtain the hyperfine electric field gradients. The calculated results are compared with experimental and other first-principles results. A description of hyperfine interactions is followed by an introduction to the electric field gradient and the perturbed angular correlation spectroscopy, explaining experimental details of this method. Next, a general description of rare earth perovskite type manganites, is presented, with emphasis on LaMnO3 and structural aspects. The theoretical basis of the computational method applied on these materials is also presented for better understanding of the results obtained. These results finish with a discussion and a conclusion. From the results and discussion we conclude that the values of the electric field gradient can be calculated with acceptable precision when compared with other first principles results on LaMnO 3 , and for CaMnO3 it is certainly possible to improve the results. The qualitative results obtained for CaMnO3, however, follow the expected variation.
year published 2007