Electronic and magnetic properties of spiral spin-density-wave states in transition-metal chains

The electronic and magnetic properties of one-dimensional (1D) 3d transition-metal nanowires are investigated in the framework of density functional theory. The relative stability of collinear and noncollinear (NC) ground-state magnetic orders in V, Mn, and Fe monoatomic chains is quantified by computing the frozen-magnon dispersion relation ΔE(q- ) as a function of the spin-density-wave vector q- . The dependence on the local environment of the atoms is analyzed by varying systematically the lattice parameter a of the chains. Electron correlation effects are explored by comparing local spin-density and generalized-gradient approximations to the exchange and correlation functional. Results are given for ΔE(q- ), the local magnetic moments μ - i at atom i, the magnetization-vector density m- (r- ), and the local electronic density of states ρiσ(ϵ). The frozen-magnon dispersion relations are analyzed from a local perspective. Effective exchange interactions Jij between the local magnetic moments μ - i and μ- j are derived by fitting the ab initio ΔE(q - ) to a classical 1D Heisenberg model. The dominant competing interactions Jij at the origin of the NC magnetic order are identified. The interplay between the various Jij is revealed as a function of a in the framework of the corresponding magnetic phase diagrams. © 2016 American Physical Society.

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