Electrical and thermal transport in a twisted heterostructure of transition metal dichalcogenide and CrI$_3$ connected to a superconductor

TL;DR

This study explores how twist angle and electric fields influence electric and thermal transport in a TMDC/CrI3 heterostructure connected to a superconductor, revealing tunable spin-valley polarized Andreev reflection and conductance.

Contribution

It demonstrates the control of spin-valley polarized Andreev reflection and conductance via twist angle, doping, and electric fields in TMDC/CrI3 heterostructures, highlighting new tunable transport phenomena.

Findings

Perfect spin valley polarized Andreev reflection over a wide bias range.

Higher thermal conductance in p-type doped structures.

Twist angle can suppress or enhance conductance depending on parameters.

Abstract

The broad tunability of the proximity exchange effect between transition-metal dichalcogenides (TMDCs) and chromium iodide (CrI$_3$) heterostructures offers intriguing possibilities for the use of TMDCs in two-dimensional magnetoelectrics. In this work, the influence of the twist angle and the gate electric field on the electric and thermal transport in a TMDC/CrI$_3$ junction is investigated using the Dirac -Bogoliubov-de Gennes equation. We show that significant amounts can be controlled by spin-splitting of band structures due to spin-orbit interaction, and that the exchange-splitting of bands arises from the proximity effect. The property of the Andreev reflection (AR) process is highly dependent on the spin valley polarized states due to spin-orbit coupling. Remarkably, perfect spin valley polarized AR is possible over a wide bias range by using a gate voltage to tune the local Fermi energy and varying the type of charge doping. The proposed structure with $p$-type doping is found to have larger spin valley polarized Andreev conductance and high thermal conductance. We further show that, depending on the TMDC material and chemical potential of the TMDC/CrI$_3$ layer, twisting can lead to suppression or a significant increase in Andreev conductance as well as enhancement of thermal conductance for chemical potentials smaller than that of the superconducting regime.