Quantum Hole Digging in Magnetic Molecular Clusters

TL;DR

This paper investigates quantum relaxation in Fe8 magnetic molecular clusters at ultra-low temperatures, introducing a new hole digging method to analyze spin state distributions and effects of spin-phonon coupling.

Contribution

It extends the hole digging technique to the thermal activated regime, enabling study of spin-phonon interactions in magnetic molecular clusters.

Findings

Observed intrinsic broadening of the hole width possibly due to nuclear spins

Demonstrated the applicability of hole digging in the thermal regime

Provided insights into spin-phonon coupling effects

Abstract

Below 360 mK, Fe8 magnetic molecular clusters are in the pure quantum relaxation regime. We showed recently that the predicted ``square-root time'' relaxation is obeyed, allowing us to develop a new method for watching the evolution of the distribution of molecular spin states in the sample. We measured the distribution P(H) of molecules which are in resonance at the applied field H. Tunnelling initially causes rapid transitions of molecules, thereby ``digging a hole'' in P(H). For small initial magnetisation values, the hole width shows an intrinsic broadening which may be due to nuclear spins. We present here hole digging measurements in the thermal activated regime which may allow to study the effect of spin-phonon coupling.