Short Time Quantum AC response of a system of Nanomagnets

TL;DR

This paper investigates how low-frequency AC magnetic fields influence the short-time magnetisation relaxation in nanomagnet ensembles, revealing effects that can help probe nuclear spin relaxation mechanisms.

Contribution

It provides a theoretical calculation of magnetisation relaxation under AC fields at low temperatures, highlighting the impact of field amplitude on relaxation dynamics.

Findings

AC fields with amplitude larger than nuclear field fluctuations significantly affect relaxation

The results suggest a method to experimentally probe nuclear spin relaxation mechanisms

Short-time relaxation behavior is strongly dependent on AC field amplitude

Abstract

We calculate the magnetisation relaxation in the short-time regime for an ensemble of nanomagnets in the presence of a low-frequency external AC biasing field, at temperatures lower than the magnetic anisotropy energy of the individual nanomagnets. It is then found that the relaxation is strongly affected by AC fields with amplitude larger than that of the $T_2$ fluctuations in the nuclear field. This will allow experimental probing of the nuclear spin relaxation mechanism.