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Proceedings Paper

Anomalous Nernst and spin Nernst effects and thermo-spin Hall conductivity in Rashba-coupled materials (Conference Presentation)
Author(s): Parijat Sengupta; Junxia Shi
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Paper Abstract

The cumulative effects of the charge, spin, and heat carried by electrons give rise to a variety of phenomena, most notably the realization of spin-driven thermoelectrics. We model the anomalous Nernst (ANE) and the spin Nernst (SNE) effects and a Seebeck-induced spin Hall conductance (SHC) in high spin-orbit coupled (soc) compounds. The lead chalcogenide, PbTe, is chosen as the representative material. PbTe films, by virtue of a large soc and narrow bulk band gap possess a significant Rashba spin-orbit coupling (RSOC) leading to a Berry curvature that induces anomalous thermal behaviour. In presence of a temperature gradient (ΔT) and magnetic field, the ANE and SNE drive thermal and spin currents - characterized by their respective coefficients - which acquire higher values for a stronger RSOC. Additionally, an extrinsic soc generated by an in-plane electric field offers a gate-like mechanism to control the anomalous thermal and spin currents. As a measure of the thermodynamic efficiency of such processes, we set up a Carnot engine that optimizes for low effective masses – which is a direct outcome of a robust intrinsic soc. Furthermore, contrary to the RSOC-originated anomalous effects, a PbTe-like gradient doped film clamped between contacts maintained at a specific ΔT exhibits a thermally-controlled SHC. The ΔT generates a Seebeck current (I-Seebeck) carried by the RSOC- spin-polarized electrons. The spin current generated by the passage of I-Seebeck is gauged via the SHC as a function of the Seebeck coefficient (S) and ΔT. A larger S manifests in a more pronounced SHC.

Paper Details

Date Published: 18 September 2018
Proc. SPIE 10732, Spintronics XI, 1073224 (18 September 2018); doi: 10.1117/12.2320897
Show Author Affiliations
Parijat Sengupta, Univ. of Illinois at Urbana-Champaign (United States)
Junxia Shi, Univ. of Illinois at Urbana-Champaign (United States)

Published in SPIE Proceedings Vol. 10732:
Spintronics XI
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi; Henri Jaffrès, Editor(s)

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