Non-equilibrium Green's functions for spin transport and dynamics
Springer Handbook of Materials. Volume 1 Methods: Theory and Modelling , Ed. W. Andreoni and S. Yip. Vol. submitted (2018)
Non-equilibrium Green's functions for spin transport and dynamics
The modeling of spintronic devices is a theoretical challenge, since one has to describe accurately both the electronic structure of the constituent materials and their charge and spin transport properties. In this chapter we present the state of the art quantum transport theory appropriate for this task. The theory is based on the so-called non-equilibrium Green’s functions (NEGF) formalism, which is combined with density functional theory (DFT) in order to provide a first principles description of materials properties. NEGF+DFT allows for the evaluation of the steady state charge- and spin-current through a quantum system at a finite applied bias voltage between the electrodes. It also describes the spin-transfer torque that flowing spins exert on localized magnetic moments, which is able to switch the magnetization of a magnetic system. In this chapter the detailed discussion about the principal methodological aspects is accompanied by the review of a number of technologically relevant applications.