Dynamics of a magnetic dimer with exchange, dipolar and Dzyalozhinski-Moriya interaction

TL;DR

This paper analyzes the switching mechanisms and rates of a magnetic dimer with exchange, dipolar, and Dzyalozhinski-Moriya interactions, providing semi-analytical expressions and comparing their efficiencies in magnetic reversal.

Contribution

It offers a comparative study of three different magnetic couplings in a dimer, including analytical expressions for switching rates and insights into energy barrier variations.

Findings

Dipole-dipole interaction results in the slowest switching rate.

Energy barriers can increase or decrease with coupling strength.

Switching mechanisms vary depending on the type of interaction.

Abstract

We investigate the dynamics of a magnetic system consisting of two magnetic moments coupled by either exchange, dipole-dipole, or Dzyalozhinski-Moriya interaction. We compare the switching mechanisms and switching rates as induced by the three couplings. For each coupling and each configuration of the two anisotropy axes, we describe the switching modes and, using the kinetic theory of Langer, we provide (semi-)analytical expressions for the switching rate. We then compare the three interactions with regard to their efficiency in the reversal of the net magnetic moment of the dimer. We also investigate how the energy barriers vary with the coupling. For the dipole-dipole interaction we find that the energy barrier may either increase or decrease with the coupling depending on whether the latter is weak or strong. Finally, upon comparing the various switching rates, we find that the dipole-dipole coupling leads to the slowest magnetic dimer, as far as the switching of its net magnetic moment is concerned.