Dipolar-controlled spin tunneling and relaxation in molecular magnets

TL;DR

This paper investigates how dipole-dipole interactions influence spin tunneling and relaxation in molecular magnets, revealing a slow relaxation process and the limited impact of nuclear spins on this behavior.

Contribution

It introduces a microscopic model using quantum mean-field approximation to analyze dipolar-controlled spin relaxation in disordered molecular magnets.

Findings

Spin coherence is lost due to strong dipole-dipole interactions.

Magnetization relaxes following a t^{3/4} law at short times.

Nuclear spins only slightly accelerate the relaxation process.

Abstract

Spin tunneling in molecular magnets controlled by dipole-dipole interactions (DDI) in the disordered state has been considered numerically on the basis of the microscopic model using the quantum mean-field approximation. In the actual case of a strong DDI spin coherence is completely lost and there is a slow relaxation of magnetization, described by t^{3/4} at short times. Fast precessing nuclear spins, included in the model microscopically, only moderately speed up the relaxation.