Resonant Magnetization Tunneling in Mn12 Acetate: The Absence of Inhomogeneous Hyperfine Broadening

TL;DR

This study investigates the relaxation rate of Mn12 acetate under magnetic fields, revealing that the tunneling mechanism is not governed by inhomogeneous hyperfine broadening as previously expected.

Contribution

It demonstrates that the resonant tunneling relaxation rate fits a Lorentzian profile without signs of hyperfine inhomogeneous broadening, challenging existing assumptions.

Findings

Relaxation rate fits Lorentzian profile

No evidence of hyperfine inhomogeneous broadening

Implication that tunneling mechanism is not solely hyperfine-driven

Abstract

We present the results of a detailed study of the thermally-assisted-resonant-tunneling relaxation rate of Mn12 acetate as a function of an external, longitudinal magnetic field and find that the data can be fit extremely well to a Lorentzian function. No hint of inhomogeneous broadening is found, even though some is expected from the Mn nuclear hyperfine interaction. This inconsistency implies that the tunneling mechanism cannot be described simply in terms of a random hyperfine field.