Energy and magnetization transport in non-equilibrium spin-chains: new perspectives on the spin-Seebeck effect

by Simone Borlenghi Garoia (KTH)

Tuesday 3 Dec 2013, 11:00 → 12:00 Europe/Stockholm

Nordita West (122:026)

Recently, it has been shown that a thermal gradient through a magnetic material can be used to manipulate its magnetization and propagate a spin current on scales up to the mm. This new phenomenon, called spin-Seebeck effect, has attracted a lot of attention for its potential applications in efficient thermoelectric conversion. On the theoretical point of view, its description is challenging, since it concerns non-equilibrium systems where the flows of electron, phonons and magnons are coupled. In this seminar, I will present some recent theoretical results on the Spin-Seebeck effect in one dimensional magnetic insulators. In those systems, a thermal gradient originates two coupled currents, of energy and magnetization, which are carried only by the dynamics of the localized spins. A simple transformation allows to describe this system as a discrete nonlinear Schroedinger equation. This formalism makes clear the conservation laws for the propagating currents and creates a connection with the fields of phononics, which investigates the transport of heat in oscillator chains. Using this formalism, we predict a new rectification effect (of energy and magnetization currents) in a novel kind of diode. our results are supported by micromagnetic simulations performed on realistic samples.