IOP Publishing, Journal of Physics: Condensed Matter, 20(13), p. 4553-4566
DOI: 10.1088/0953-8984/13/20/316
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The influence of ligand states on the orbital magnetism of a 3d atom in a ferromagnetic compound has been studied using an ab initio technique. It is shown, using VAu4, MnAu4 and VPt3 as examples, that the large spin-orbit coupling of the 5d atom is responsible for the reversal of the coupling between the V(Mn) spin and orbital moments with respect to that for similar compounds. The VAu4 compound has a large magneto-crystalline anisotropy (MCA) and the spin-up states are completely occupied, which makes its MCA proportional to the orbital moment anisotropy as stated by Bruno's perturbative formula (Bruno P 1989 Phys. Rev. B 39 865). For the latter compound it is also shown that a partial substitution of copper for gold decreases the vanadium orbital moment and hence the MCA. The ligand state effects on the orbital moment together with this alloying procedure may initiate a new approach in the search for ultra-soft magnetic materials.