Origin of magnetic switching cascades in tetrahedral CoFe nanostructures

TL;DR

This study investigates the magnetic switching behavior of 3D tetrahedral CoFe nanostructures, revealing cascade phenomena near zero field through experiments and simulations, and models the behavior with a macrospin approach.

Contribution

It introduces a macrospin model based on superimposed Stoner-Wohlfarth particles to explain complex magnetic switching in tetrahedral nanostructures.

Findings

Cascading magnetic switching observed near zero field.

Reproduction of hysteresis loops via micromagnetic simulations.

Identification of vortex-type ground states.

Abstract

We present a comprehensive study of small-scale three-dimensional (3D) tetrahedral CoFe nanostructure arrays prepared by focused electron beam-induced deposition (FEBID) and placed in two distinct orientations with respect to the direction of an external magnetic field. Using ultra-sensitive micro-Hall magnetometry we obtain angular-dependent magnetic stray field hysteresis loops that show characteristic cascading magnetic switching close to zero magnetic field. By employing micromagnetic simulations we could reproduce the hysteresis loops and identify characteristic field dependent magnetic configurations including a vortex-type groundstate. From this we derive a coarse-graining macrospin model and show that the complex switching behavior can be explained by the reorientation dynamics of non-interacting uniaxial anisotropic magnetic grains modeled as a superposition of Stoner-Wohlfarth particles.