Noncollinear magnetic structures in amorphous iron and iron-based alloys

Abstract

We present a novel technique for calculating noncollinear spin structures in itinerant magnets. Our approach is based on a tight-binding Hubbard Hamiltonian constructed by a canonical transformation of a self-consistent spin-polarized linear muffin-tin orbital Hamiltonian to a tight-binding form, and on a real-space recursion technique for the self-consistent calculation of the local exchange splitting and local moments. Applications to amorphous Fe at different densities and to Fe-Zr alloys of different compositions are presented. Our results show that with increasing density amorphous Fe shows a continuous transition from a ferromagnetic to an asperomagnetic and finally to a speromagnetic (spin-glass-like) state. This spin-glass state exists over a considerable range of densities before the system becomes paramagnetic. Similar transitions are observed in amorphous Fe-Zr alloys with increasing Fe content.