Magnetic and electronic structure properties of strontium cobaltites from first principles

VÍCTOR PARDO; PABLO M. BOTTA; DANIEL BALDOMIR; ALBERTO PIÑEIRO; JOSÉ RIVAS; JUAN E. ARIAS

Houston, Estados Unidos

Congreso; Strongly Correlated Electron Systems (SCES07); 2007

Ab initio calculations were performed in two strontium cobaltites that crystallize in a quasi-onedimensional hexagonal Sr6Co5O15 and a perovskite-type Sr2Co2O5 structure. The electronic structure calculations were carried out by means of a full-potential augmented plane wave plus local orbitals (FP-APW+lo) method with the software WIEN2k. Their chemical stability was analyzed by total energy calculations confirming the tendency to form Co3O4 during the synthesis. The electronic structure of the materials and their magnetic properties were analyzed. Sr2Co2O5 is a G-type antiferromagnet. The possibility of spin state transitions in this Co3+ compound was explored by studying different spin state configurations in various magnetic orderings. The most stable configuration is a high spin state for our zero temperature calculations. Sr6Co5O15 presents interesting magnetic and electronic structure properties due to its quasi-onedimensional frustrated hexagonal structure, like Ising-type anisotropy and the possibility of different magnetic couplings along the chains. The importance of spin-orbit effects in explaining its magnetic properties is shown.