Magnetic and electronic properties of substitutional FeN cluster impurities in Cr: Transition from antiferromagnetic to ferromagnetic FeN

We present a study of the magnetic and electronic properties of FeN clusters embedded in antiferromagnetic bcc Cr. The spin-polarized charge distribution is determined self-consistently by solving a realistic spd-band model Hamiltonian including intra-atomic Coulomb interactions in the unrestricted Hartree-Fock approximation. For all the studied clusters (N≤51), the local magnetc moments at Fe atoms close to the Fe-Cr interface, as well as the average magnetic moment of the FeN impurity, are reduced with respect to the Fe bulk magnetization. The magnetic order within FeN changes from antiferromagneticlike to ferromagneticlike with increasing cluster size. The calculated critical size for this transition is Nc6. Results for the spatial distribution of the magnetic moments and for the local electronic densities of states are given for different N. The role of the structural and chemical local environment of the atoms on the electronic and magnetic properties is discussed, and our results are compared with those found for Fe/Cr multilayers. Some of the implications of the present study for magnetic alloys and ferromagnetic clusters on surfaces are pointed out. © 1994 The American Physical Society.

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