First principle and series expansions calculations of electronic and magnetic properties of Co(Ni)Cr_2O_4 spinels

摘要

Self-consistent ab initio calculations, based on Density Functional Theory approach and using full potential Linear Augmented Plane Wave method, are performed to investigate both electronic and magnetic properties of the CoCr_2O_4 and NiCr_2O_4. Magnetic moment considered to lie along (010) axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions calculations to compute other magnetic parameters. The high temperature series expansions of the magnetic susceptibility are given up to seventh order series in (x=J_(Mn-Mn)/k_BT) of CoCr_2O_4 and NiCr_2O_4. The Néel temperature T_N(K) and critical exponent γ associated with the magnetic susceptibility are obtained as well for both compounds.