Current-induced torques in magnetic Weyl semimetal tunnel junctions

TL;DR

This paper investigates how the unique electronic states of magnetic Weyl semimetals influence current-induced torques in tunnel junctions, revealing novel torque behaviors and potential for energy-efficient spintronics.

Contribution

It demonstrates the role of Weyl semimetal bulk chirality and Fermi arc states in governing torque sign and magnitude, introducing new physics for multilayered spintronic devices.

Findings

Bulk chirality determines torque sign.

Large field-like torques exceed conventional limits.

Fermi arc spin texture affects torque dependence.

Abstract

We study the current-induced torques in asymmetric magnetic tunnel junctions containing a conventional ferromagnet and a magnetic Weyl semimetal contact. The Weyl semimetal hosts chiral bulk states and topologically protected Fermi arc surface states which were found to govern the voltage behavior and efficiency of current-induced torques. We report how bulk chirality dictates the sign of the non-equilibrium torques acting on the ferromagnet and discuss the existence of large field-like torques acting on the magnetic Weyl semimetal which exceeds the theoretical maximum of conventional magnetic tunnel junctions. The latter are derived from the Fermi arc spin texture and display a counter-intuitive dependence on the Weyl nodes separation. Our results shed light on the new physics of multilayered spintronic devices comprising of magnetic Weyl semimetals, which might open doors for new energy efficient spintronic devices.