Comment on "Tunnel Window's Imprint on Dipolar Field Distributions"

TL;DR

This paper critiques a previous Monte Carlo simulation study of dipolar interactions, emphasizing that the physics of tunneling relaxation in nanomagnets differs significantly from the simplified noise model used earlier.

Contribution

It clarifies the differences in physical mechanisms between tunneling relaxation in nanomagnets and the noise field approximation in prior simulations.

Findings

Highlights the distinct physics of tunneling in nanomagnets.

Critiques the uniform noise field approximation.

Emphasizes the importance of tunneling hole formation.

Abstract

In a recent letter Alonso et al. (Phys. Rev. Lett. 87, 097205 (2001)) present Monte Carlo simulations for interacting dipoles. Short-time relaxation was caused by a simple noise field, acting uniformly over an "energy window" of small width (to simulate the fluctuating nuclear spin bias). However, the physics of the tunneling relaxation of an ensemble of tunneling nanomagnets or magnetic molecules (as well as of the "tunneling hole" formation) is different and here we discuss this point.