Dependence of the Switching Current Density on the Junction Sizes in Spin Transfer Torque

TL;DR

This study uses micromagnetic simulations to reveal that the switching current density in spin transfer torque nanopillars strongly depends on junction size due to complex spin configurations and dynamics, contrary to macro spin model predictions.

Contribution

It demonstrates the size dependence of switching current density caused by spin wave excitations and shape effects, providing new insights into spin transfer torque switching mechanisms.

Findings

Switching current density varies significantly with junction size.

Spin wave excitation influences the switching process.

Junction shape affects spin configurations and dynamics.

Abstract

We investigate the dependence of switching current density on the junction sizes in the spin transfer torque nanopillar structures by using micromagnetic simulations. While the macro spin model predicts weak dependence of switching current density on the junction sizes, we find that the switching current density is a sensitive function of the junction sizes. It can be explained with the complicated spin configurations and dynamics during the switching process. The detail spin configurations and dynamics are determined by spin wave excitation with the finite wave vector, which is related with the exchange coupling energy and junction shape.