Generation of spin currents by a temperature gradient in a two-terminal device

Rafael E. Barfknecht,Angela Foerster,Nikolaj T. Zinner,Artem G. Volosniev

doi:10.1038/s42005-021-00753-7

Abstract

Theoretical and experimental studies of the interaction between spins and temperature are vital for the development of spin caloritronics, as they dictate the design of future devices. In this work, we propose a two-terminal cold-atom simulator to study that interaction. The proposed quantum simulator consists of strongly interacting atoms that occupy two temperature reservoirs connected by a one-dimensional link. First, we argue that the dynamics in the link can be described using an inhomogeneous Heisenberg spin chain whose couplings are defined by the local temperature. Second, we show the existence of a spin current in a system with a temperature difference by studying the dynamics that follows the spin-flip of an atom in the link. A temperature gradient accelerates the impurity in one direction more than in the other, leading to an overall spin current similar to the spin Seebeck effect.

Highlights

Theoretical and experimental studies of the interaction between spins and temperature are vital for the development of spin caloritronics, as they dictate the design of future devices
The system is completely polarized, and by assumption there is a time-independent temperature gradient across the link. a At t = 0 a particle at the center of the system has its internal state changed by a spin-flip pulse. b Due to the presence of the temperature gradient, one observes a spin current across the system, which is caused by the motion of the impurity from the low- to the high-temperature region
We argue that the dynamics of the system can be obtained by considering a spin chain whose exchange coefficients depend on temperature

Summary

Introduction

Theoretical and experimental studies of the interaction between spins and temperature are vital for the development of spin caloritronics, as they dictate the design of future devices. We employ a basic theoretical model, which does not manifest any heat and charge transfer (in contrast to the DMRG study performed in Ref. 16, for instance) Instead, it exhibits certain features of the magnon-driven spin Seebeck effect[17]. For convenience of the reader, let us summarize the main findings of the paper: a) we introduce an effective model for studying the time dynamics of a strongly interacting onedimensional system at finite temperatures This allows us to circumvent the need to explicitly include excited states in the analysis; b) Using this model, we present a microscopic theory in which a spin current is induced by a temperature gradient

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