Theory of spin transport induced by a temperature gradient

Abstract

Spin transport driven by the temperature gradient in ferromagnetic metals is studied based on a microscopic theory. It is shown that the temperature gradient works as an effective field equivalent to the electric field as for both the spin current generation and the spin relaxation torque. The thermally driven contribution of the spin current and the relaxation torque are thus proportional to ∇T and ∇ 2 T , respectively.

Ultrafast spin-transfer torque driven by femtosecond pulsed-laser excitation

“…In the literature, different types of spin Seebeck effects have been proposed, originating from temperature differences at magnetic/ non-magnetic interfaces 12 , magnon-driven spin currents due to a bulk temperature gradient 13,18 or spin-dependent Seebeck coefficients combined with temperature gradients within the magnetic thin films 14,15,39 . The magnonic or spin-wave-like effects appear to be dominant on long lengthscales (several micro-to millimeters) or in magnetic insulators, whereas the interface effects have shown to be too weak to explain experimental data on similar structures (metallic magnetic multilayers) as used in the present experiments 14 .…”

Spin caloritronics

“…Thermoelectric phenomena at constrictions and interfaces are obtained by replacing the gradients by differences and the conductivities by conductances. The spin dependence of the thermoelectric properties in isotropic and monodomain metallic ferromagnets can be expressed in the two-current model of majority and minority spins [1,7,12,13]:…”

Tunneling magnetothermopower in magnetic tunnel junctions

“…Also, inspired by an aforementioned experiment [13], theoretical descriptions of thermal spin transport for ferromagnet/insulator/semiconductor MTJs have also been developed [22,29]. Finally, theory regarding all-metallic junctions has as well been recently studied [23,24,30,31].…”