Theory of spin-polarized thermal transport in ferromagnetic metallic heterostructures

• Applicant: Professor Dr. Jaroslav Fabian
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2011 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 198359765

There has been significant experimental progress on investigating spin-polarized thermal transport in ferromagnetic metals. In this proposal we request funding to perform system-atic and comprehensive calculations of the spin-polarized thermal transport in ferromag-netic metal heterostructures. On a phenomenological level, we will generalize the stan-dard spin injection model to include thermal currents in realistic device settings, investi-gate the effects of the boundary conditions on the spin accumulation and the spin Hall voltages in these systems. In addition, we plan to study ac and transient phenomena which will provide important information about the spin relaxation processes and thermally induce spin accumulation. Among particular goals are finding realistic spin Seebeck coef-ficients in the F/N/F junctions, in various regimes of contact and tunneling resistances, to give the benchmark to sort out electronic and magnonic contributions to the detected spin voltage signals. We will also investigate systems with space charges, such as Schottky barriers and ferromagnetic junction diodes and transistors; in these systems the standard theory of the spin-polarized thermal transport has to be generalized to include (self-consistently) the built in electric fields. On a microscopic level, we will investigate the magnon drag and the spin-phonon drag and their interplay with thermal and spin transport in ferromagnetic metallic heterostructures. The relevance of these mechanisms for the thermopower and the control system parameters will be established by developing micro-scopic model calculations. Special attention will be devoted to the role of these mecha-nisms at the F/N interfaces. The effects of disorder and spin-orbit interaction in junctions with structure inversion asymmetry will also be incorporated. In particular, we will explore the possibility of new phenomena emerging from the combined action of the SOI and the drag mechanisms. These calculations will be performed by using both the Boltzmann and Kubo linear-response formalisms. The obtained results will be used to complement the phenomenological theory of thermal spin injection.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1538: Spin Caloric Transport (SpinCaT)