Electronic State of Mn Impurity in Ferromagnetic Ni-Co Alloys –Localized Moment Behavior–

The existence of two magnetic states and the effect of the local atomic environment on these states for atoms in random ferromagnetic alloys are investigated in the Hartree-Fock approximation. Electronic states of a single impurity Mn atom in Ni-Co alloys are calculated with varying the numbers of Ni and Co atoms on the nearest neighbor sites and the alloy concentration. From an energy consideration, it is concluded that the magnetic moment of the Mn is parallel to the bulk magnetization in Ni-rich environment, while it is antiparallel in Co-rich ones.