Spin quantum tunneling in single molecular magnets: fingerprints in transport spectroscopy of current and noise

TL;DR

This paper investigates how quantum tunneling in single molecular magnets affects transport spectroscopy, revealing oscillations and false resonances in current and noise, and showing conditions where tunneling suppresses transport.

Contribution

It provides new insights into the signatures of quantum tunneling in transport measurements of single molecular magnets, including the effects of anisotropy symmetry.

Findings

Transport spectroscopy shows quantum tunneling signatures at low temperatures.

Quantum tunneling causes oscillations and fake resonances in current and noise.

High symmetry in anisotropy can suppress transport entirely.

Abstract

We demonstrate that transport spectroscopy of single molecular magnets shows signatures of quantum tunneling at low temperatures. We find current and noise oscillations as function of bias voltage due to a weak violation of spin selection rules by quantum tunneling processes. The interplay with Boltzmann suppression factors leads to fake resonances with temperature-dependent position which do not correspond to any charge excitation energy. Furthermore, we find that quantum tunneling can completely suppress transport if the easy-plane anisotropy has a high symmetry.