First-principles relativistic study of spin waves in thin magnetic films

作     者：L. Udvardi L. Szunyogh K. Palotás P. Weinberger 

作者机构：Department of Theoretical Physics and Center for Applied Mathematics and Computational Physics Budapest University of Technology and Economics Budafoki út 8 H-1111 Budapest Hungary Center for Computational Materials Science Technical University Vienna Gumpendorfer Str. 1a A-1060 Vienna Austria 

出 版 物：《Physical Review B》 (物理学评论B辑：凝聚态物质与材料物理学)

年 卷 期：2003年第68卷第10期

页      面：104436-104436页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

主　　题：.itinerant on-site classical spin spin-wave uniaxial first-principles spin waves magnetic films fully relativistic Magnetic force order with respect Relativistic Study polar and azimuthal 

摘      要：In order to study spin-wave excitations of itinerant ferromagnets a relativistic first-principles method based on the adiabatic approach is presented. The derivatives of the free energy up to second order with respect of the polar and azimuthal angles are derived within the framework of the magnetic force theorem and the fully relativistic Korringa-Kohn-Rostoker method. Exchange and spin-orbit coupling are thus incorporated on equal footing in the Hamiltonian. Furthermore, a detailed comparison to classical spin Hamiltonians is given and it is shown that the magnetocrystalline anisotropy energy contains contributions from both the on-site anisotropy and the off-site exchange coupling terms. The method is applied to an Fe monolayer on Cu(001) and Au(001) surfaces and for a Co monolayer on Cu(001). The calculations provide with the gap at zero wave number due to the spin-orbit coupling and uniaxial anisotropy energies in good agreement with the results of the band energy difference method. It is pointed out that the terms in the spin-wave Hamiltonian related to the mixed partial derivatives of the free energy, absent within a nonrelativistic description, introduce an asymmetry in the magnon spectrum with respect to two in-plane easy axes. Moreover, in the case of an in-plane magnetized system the long-wavelength magnons are elliptically polarized due to the difference of the second-order uniaxial and fourth-order in-plane magnetic anisotropy.