Ferromagnetism in Monatomic Chains: Spin-Dependent Bandwidth Narrowing/Broadening

Abstract

We have analyzed the role of band narrowing/broadening in the magnetic and electronic properties of low dimensional itinerant strongly correlated electronic systems, which is particularly important in 3d transition elements. Density functional theory and mean field results have been coupled to explain the magnetic phenomenon in a one-dimensional monatomic chain of 3d transition elements Sc, Ti, V, Cr, Mn, Fe, Co, and Ni. We found that in the ferromagnetic ground state not only the band splitting but also the relative band narrowing/broadening play a crucial role, and the bandwidths of both spins become different as a manifestation of correlated spin hopping interaction. For less than the half-filled band (i.e., for Sc, Ti, V, and Cr), the up spin band broadens, and the down spin band narrows. For the (half and) more than half filled band (i.e., for Mn, Fe, Co, and Ni), the down spin band broadens, and the up spin band narrows. As a result, (in most of the cases) only one spin channel is present for conduction, showing ferromagnetism which could be useful for spintronics.