Nonlinear heat transport in ferromagnetic-quantum dot-superconducting systems

Sun-Yong Hwang,David Sánchez

doi:10.1088/1742-6596/969/1/012139

Abstract

We analyze the heat current traversing a quantum dot sandwiched between a ferromagnetic and a superconducting electrode. The heat flow generated in response to a voltage bias presents rectification as a function of the gate potential applied to the quantum dot. Remarkably, in the thermally driven case the heat shows a strong diode effect with large asymmetry ratios that can be externally tuned with magnetic fields or spin-polarized tunneling. Our results thus demonstrate the importance of hybrid systems as promising candidates for thermal applications.

Highlights

Control of heat flow is a key goal in modern quantum electronics [1, 2]
We investigate a ferromagnetic-quantum dot-superconducting (F-D-S) junction and show that this system can work as an efficient heat diode both for charge and spin transport
This device provides means to control the heat flow in a unidirectional way. This is akin to the diode effects of the thermoelectric currents [32]

Summary

Introduction

Control of heat flow is a key goal in modern quantum electronics [1, 2]. Electrons carry energy in addition to charge and their transport can be manipulated electrically [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13] or thermally [14, 15, 16, 17, 18, 19]. ). Note that the leading order nonvanishing Andreev thermal conductance can only be given by the cross coupling term MAσ to the subgap nonlinear electric current [31]. This implies that in the isoelectric case V = 0 the subgap thermal transport is entirely blocked and the thermal heat current will be activated by the quasiparticle contributions only. If we apply high enough thermal gradient for a nonzero V , quasiparticles dominantly contribute to the heat transport after the competing regime is over where JQ −JA and JQs −JAs (see Fig. 3) Beyond this competing regime, large heat and spin heat currents can be generated in our device from quasiparticle tunneling.

Results and discussion

Nonlinear Peltier effect

Conclusions