Finite-temperature surface magnetism of Fe(100)

Magnetic and one-electron properties of Fe(100) at finite temperatures are studied by means of the functional-integral method within the static and single-site approximations, but using the realistic tight-binding canonical d band model. Calculations of average magnetic moments on the first ten layers of the semi-infinite BCC lattice predict that the surface moment, which is enhanced at T=0 K compared with the bulk one, decreases more rapidly than the bulk upon heating. The temperature-induced change in the spectral density is shown to depend on the wavevector in the two-dimensional surface Brillouin zone. The exchange-split peaks in the Gamma point surface spectral densities approach each other as the Stoner bands when temperature is raised whereas the surface-state positions at Delta and Sigma are almost stationary. It is pointed out that the surface effect can play important roles in discussing angle-resolved photoemission experiments probing 'bulk' band structures of Fe.