Ab-initio calculation of effective exchange interactions, spin waves, and Curie temperature in L2(1)- and L1(2)-type local moment ferromagnets

作者：Galanakis I^*; Sasioglu E

来源：Journal of Materials Science, 2012, 47(21): 7678-7685.

DOI：10.1007/s10853-012-6285-6

Employing first-principles electronic structure calculations in conjunction with the frozen-magnon method, we study the effective exchange interactions and spin waves in local moment ferromagnets. As prototypes we have chosen three L2(1)-type full Heusler alloys Cu2MnAl, Ni2MnSn, and Pd2MnSn, and the L1(2)-type XPt3 compounds with X = V, Cr, and Mn. We have also included CoPt3 which is a usual ferromagnet. In all compounds due to the large spatial separation (similar to 4 ) of the magnetic transition-metal atoms, the 3d states belonging to different atoms overlap weakly and as a consequence the exchange coupling is indirect, mediated by the sp electrons. Calculated effective exchange parameters are long range and show RKKY-type oscillations. The spin-wave dispersion curves are in reasonable agreement with available experimental data. Using the calculated exchange parameters, we have estimated the Curie temperatures within both the mean-field and the random-phase approximations. In local moment ferromagents deviations of the estimated Curie temperature with respect to the available experimental data occur when the ground-state electronic structure calculations overestimate the values of the spin magnetic moments as in VPt3.

• 出版日期2012-11