Angular Dependence of Switching Properties in Single Fe Nanopillars

TL;DR

This study uses micromagnetic simulations to analyze how the angle of an applied magnetic field affects the magnetization reversal process in Fe nanopillars, revealing angle-dependent switching behaviors.

Contribution

It provides detailed finite-temperature micromagnetic simulation results on angular dependence of switching in Fe nanopillars, extending understanding beyond the coherent rotation model.

Findings

Switching field increases with angle from 0° to 90°.

Reversal initiates at endcaps at low angles and along the entire length at 90°.

Simulation results align with experimental observations.

Abstract

The continued increase in areal densities in magnetic recording makes it crucial to understand magnetization reversal in nanoparticles. We present finite-temperature micromagnetic simulations of hysteresis in Fe nanopillars with the long axis tilted at angles from 0 degrees to 90 degrees to the applied sinusoidal field. The field period is 15 ns, and the particle size is 9 x 9 x 150 nm. The system is discretized into a rectangular pillar of 7 x 7 x 101 spins each with uniform magnetization. At low angles, reversal begins at the endcaps and proceeds toward the center of the particle. At ninety degrees, reversal proceeds along the entire length of the particle (save at the ends). The switching field was observed to increase over the entire range of angles, consistent with recent experimental observations. A second, lower-resolution micromagnetic simulation with 1 x 1 x 17 spins, does not agree with experiment, but shows behavior very similar to that of the Stoner-Wohlfarth model of coherent rotation.