Spintronic nanodevices for energy-harvesting

M. V. COSTACHE; G. BRIDOUX; I. NEUMANN; S. O. VALENZUELA

Sevilla

Congreso; VII Reunión Grupo Especializado de Física de Estado Sólido; 2012

Spin related effects have been studied using electrical transport methods, by measuring thespin diffusing length in metals and semiconductors. In addition to electrical transport, thethermoelectric properties of magnetic materials are increasingly gathering more attention.There, magnons are believed to play an essential role. However, despite intensive studies onthe spin transport, the coupling between electrons and magnons in ferromagnetic metalsremains poorly known. We have studied the contribution of magnons to electrical and thermaltransport in devices which consist of nano-sized permalloy wires with distinct coercive fields.At room temperature, we observe that the longitudinal magnetoresistance decreases linearlywith magnetic field, because of a reduction of electron-magnon scattering processes due tomagnon damping at high fields. We correlate these results with the Seebeck signal upon theapplication of a thermal gradient which gives the dependence of electron-magnon couplingwith temperature. At low temperatures (T), the magnon drag effect is evident in the T3/2power dependence of the measured signal. Whereas, above T=200K the magnon contributionis reduced because of magnon momentum loss from magnon-magnon scattering. Theseresults demonstrate the feasibility of directly converting magnon dynamics of nanomagnetsinto an electrical signal and could pave the way to novel thermoelectric devices for energyharvesting