Ab Initio Study Of High-Field Nmr Shift Of Co-59 In The Ferromagnetic Heusler Alloy Co2tiga

The high-field NMR shift of Co-59 in the ferromagnetic state of the Hensler alloy Co2TiGa has been calculated to be +0.65% by local density approximation (LDA) involving the spin-orbit interaction based on density functional theory (DFT) and Korringa-Kohn-Rostoker (KKR) Green's function method. This value explains the experimental value of +0.83% semiquantitatively. The high-field NMR shift of Co-59 is shown to be related closely with the net polarizations of Co-d and Co-s spin states only at the Fermi energy epsilon(F). The observed positive shift is shown to be a manifestation of the half-metallic character of the band structure inherent in Co-based Heusler alloys, where the spin-resolved partial density of states of s-electrons with up spin, D-S up arrow(epsilon(F)), is much larger than D-S down arrow(epsilon(F)), resulting in an important positive contribution to the field-induced hyperfine field.