Macroscopic Quantum Coherence in Molecular Magnets

TL;DR

This paper investigates macroscopic quantum coherence in molecular magnets under magnetic fields, providing semi-classical predictions, experimental measurement methods, and discovering a new quantum phase from fluctuations.

Contribution

It offers detailed semi-classical analysis of tunnel splitting and introduces a new quantum phase due to fluctuations in antiferromagnetic molecular magnets.

Findings

Tunnel splitting varies with magnetic field strength.

Tunneling dynamics can be measured via magnetization and specific heat.

A new quantum phase arising from fluctuations is identified.

Abstract

We study macroscopic quantum coherence in antiferromagnetic molecular magnets in the presence of magnetic fields. Such fields generate artificial tunnel barriers with externally tunable strength. We give detailed semi-classical predictions for the tunnel splitting in various regimes for low and high magnetic fields. We show that the tunneling dynamics of the Neel vector can be directly measured via the static magnetization and the specific heat. We also report on a new quantum phase arising from fluctuations. The analytic results are complemented by numerical simulations.