Heat-driven spin currents on large scales

Abstract

Using a three-current model (i.e. heat, spin-up and spin-down electrons) the thermodynamics of irreversible processes predicts that a temperature gradient gives rise to a spin current on large scales, in particular under the conditions used to measure the spin Seebeck effect. Diffusive currents on large scales are common in thermochemistry. The proportionality between the diffusion current and the gradient of the chemical potential is known as the Soret effect or thermophoresis. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Brechet and Ansermet show that a three-current model of heat, spin-up and spin-down currents predicts the spin polarisation current to exist on large scales and to be proportional to the temperature gradient, corresponding to a spin Soret effect. They establish the existence of the spin current driven by a heat current over large distances in the absence of a charge current and at equilibrium of the spin channels. Thus, a heat current may also affect the magnetisation. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.