A.C. susceptibility as a probe of low-frequency magnetic dynamics

TL;DR

A.C. susceptibility is a valuable experimental technique for investigating slow magnetic dynamics in various systems, especially useful for studying collective behaviors and frustrated magnetic states at low frequencies.

Contribution

This paper reviews the theoretical foundations and diverse applications of a.c. susceptibility in probing low-frequency magnetic dynamics across different materials.

Findings

Effective in studying slow magnetic processes

Useful for analyzing collective magnetic objects

Provides insights into frustrated systems like spin glasses

Abstract

The experimental technique of a.c. susceptibility can be used as a probe of magnetic dynamics in a wide variety of systems. Its use is restricted to the low-frequency regime and thus is sensitive to relatively slow processes. Rather than measuring the dynamics of single spins, a.c. susceptibility can be used to probe the dynamics of collective objects, such as domain walls in ferromagnets or vortex matter in superconductors. In some frustrated systems, such as spin glasses, the complex interactions lead to substantial spectral weight of fluctuations in the low-frequency regime, and thus a.c. susceptibility can play a unique role. We review the theory underlying the technique and magnetic dynamics more generally and give applications of a.c. susceptibility to a wide variety of experimental situations.