Anisotropic properties of spin avalanches in crystals of nanomagnets

TL;DR

This paper investigates how the anisotropic properties of nanomagnet crystals influence spin avalanches, including magnetic deflagration and detonation speeds, considering various angles of an external magnetic field.

Contribution

It provides a theoretical analysis of anisotropic effects on spin avalanches, deriving analytical formulas and exploring the impact on deflagration and detonation behaviors.

Findings

Anisotropic properties cause directional dependence of deflagration speed.

Analytical formulas for small angles are derived.

Magnetic detonation characteristics vary with field orientation.

Abstract

Anisotropy effects for spin avalanches in crystals of nanomagnets are studied theoretically with the external magnetic field applied at an arbitrary angle to the easy axis. Starting with the Hamiltonian for a single nanomagnet in the crystal, the two essential quantities characterizing spin avalanches are calculated: the activation energy and the Zeeman energy. The calculation is performed numerically for the wide range of angles and analytical formulas are derived within the limit of small angles. The anisotropic properties of a single nanomagnet lead to anisotropic behavior of the magnetic deflagration speed. Modifications of the magnetic deflagration speed are investigated for different angles between the external magnetic field and the easy axis of the crystals. Anisotropic properties of magnetic detonation are also studied, which concern, first of all, temperature behind the leading shock and the characteristic time of spin switching in the detonation.