Suppression of Quantum Phase Interference in Molecular Magnets Fe₈ with Dipolar-Dipolar Interaction

TL;DR

This paper investigates how dipolar interactions cause decoherence in quantum tunneling of molecular magnets Fe8, explaining the suppression of quantum interference effects observed experimentally.

Contribution

It introduces a model incorporating dipolar interactions to explain the suppression of quantum phase interference in Fe8 molecular magnets.

Findings

Dipolar interactions smear the oscillation of tunnel splitting.

Decoherence driven by dipolar interactions suppresses quantum interference.

Explains absence of predicted quenching points in experiments.

Abstract

Renormalized tunnel splitting with a finite distribution in the biaxial spin model for molecular magnets is obtained by taking into account the dipolar interaction of enviromental spins. Oscillation of the resonant tunnel splitting with a transverse magnetic field along the hard axis is smeared by the finite distribution which subsequently affects the quantum steps of hysteresis curve evaluated in terms of the modified Landau-Zener model of spin flipping induced by the sweeping field. We conclude that the dipolar-dipolar interaction drives decoherence of quantum tunnelling in molcular magnets Fe₈, which explains why the quenching points of tunnel spliting between odd and even resonant tunnelling predcited theoretically were not observed experimentally.