The superferromagnetic state in the ensemble of oriented Stoner-Wohlfarth particles: a coercivity due to phase stability

TL;DR

This paper investigates the superferromagnetic state in oriented Stoner-Wohlfarth particles, revealing that phase stability anomalies cause unusual coercivity angular dependence in granular films above the blocking temperature.

Contribution

It introduces the concept of phase stability singularity as the cause of anomalous coercivity behavior in superferromagnetic ensembles of interacting particles.

Findings

Anomalous angular dependence of coercivity observed experimentally.

Phase stability loss causes the coercivity anomaly.

Superferromagnetic state stability is linked to critical field behavior.

Abstract

It is observed experimentally that the coercive field has an anomalous angular dependence at temperatures above the blocking temperature in physically nonpercolated granular films CoFeB-SiO$_{2}$ with anisotropic granules oriented in the same direction. It is shown that the anomaly is determined by the singularity of an angular dependence of the critical field causing the absolute loss of phase stability of the superferromagnetic state of an ensemble of interacting superparamagnetic granules.