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 lowfrequency 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 lowfrequency regime, and thus a.c. susceptibility can play a unique role. This comprehensive review covers the theory underlying the technique and gives applications to a wide variety of experimental situations.
A.C. susceptibility as a probe of low-frequency magnetic dynamics
C. V. Topping and S. J. Blundell
J. Phys.: Condens. Matter 31, 013001 (2019)