Efficient domain wall motion in asymmetric magnetic tunnel junctions with vertical current flow

TL;DR

This paper investigates how asymmetry in magnetic tunnel junctions enhances domain wall motion driven by vertical current flow, using combined quantum transport and magnetization dynamics models.

Contribution

It demonstrates that increasing MTJ asymmetry results in a linear voltage-dependent field-like torque and improved domain wall displacement efficiency.

Findings

Asymmetry enhances domain wall displacement.

Linear-in-voltage field-like torque observed.

Improved bidirectional propagation of domain walls.

Abstract

In this paper, we study the domain wall motion induced by vertical current flow in asymmetric magnetic tunnel junctions. The domain wall motion in the free layer is mainly dictated by the current-induced field-like torque acting on it. We show that as we increase the MTJ asymmetry, by considering dissimilar ferromagnetic contacts, a linear-in-voltage field-like torque behavior is accompanied by an enhancement in the domain wall displacement efficiency and a higher degree of bidirectional propagation. Our analysis is based on a combination of a quantum transport model and magnetization dynamics as described by the Landau-Lifshitz-Gilbert equation, along with comparison to the intrinsic characteristics of a benchmark in-plane current injection domain wall device.