Resonant Acoustic Wave Assisted Spin-Transfer-Torque Switching of Nanomagnets

TL;DR

This paper demonstrates through simulations that combining resonant surface acoustic waves with spin-transfer-torque can significantly reduce energy consumption in switching nanomagnet states, enhancing the efficiency of magnetic memory devices.

Contribution

It introduces a novel method of using resonant acoustic waves to assist spin-transfer-torque switching, reducing energy dissipation in magnetic tunnel junctions.

Findings

Resonant surface acoustic waves induce magnetization precession in nanomagnets.

The combined approach reduces the required STT current density for switching.

The method maintains high switching probability at room temperature.

Abstract

We report the possibility of achieving an order of magnitude reduction in the energy dissipation needed to write bits in perpendicular magnetic tunnel junctions (p-MTJs) by simulating the magnetization dynamics under a combination of resonant surface acoustic waves (r-SAW) and spin-transfer-torque (STT). The magnetization dynamics were simulated using the Landau-Lifshitz-Gilbert equation under macrospin assumption with the inclusion of thermal noise. The resonant magnetization dynamics in the magnetostrictive nanomagnet build over few 10s of cycles of SAW application that drives the magnetization to precess in a cone with a deflection of ~45 degrees from the perpendicular direction. This reduces the STT current density required to switch the magnetization direction without increasing the STT application time or degrading the switching probability in the presence of room temperature thermal noise. This could lead to a pathway to achieve energy efficient switching of spin transfer torque random access memory (STTRAM) whose lateral dimensions can be scaled aggressively despite using materials with low magnetostriction by employing resonant excitation.