Spin-Pair Tunneling in Mn$_3$ Single-Molecule Magnet

TL;DR

This paper reports the observation of spin-pair tunneling in Mn3 single-molecule magnets, revealing concerted two-spin tunneling phenomena and their unique quantum properties, expanding understanding of quantum tunneling in magnetic systems.

Contribution

It demonstrates the existence of spin-pair tunneling in a Mn3 single-molecule magnet with a 2D exchange network, showing a novel quantum tunneling mechanism involving two spins simultaneously.

Findings

Observation of extra quantum tunnelings via ac susceptibility.

Spin-pair tunneling involves two spins transitioning simultaneously.

The splitting interval is half of single-spin tunneling, analogous to flux quantum relationships.

Abstract

We report spin-pair tunneling observed in Mn$_3$ single-molecule magnet, which is a crystal with 2D network of identical exchange coupling. We observed a series of extra quantum tunnelings by the ac susceptibility measurements, and demonstrated these are concerted tunnelings of two spins taking place from the same initial state to the same final state simultaneously. The resonant field of spin-pair tunneling can be expressed as $H_z=lD/g\mu_{0}\mu_{B}+(n_{\downarrow}-n_{\uparrow})JS/2{g\mu_{0}\mu_{B}}$, and the splitting interval ($|J|S/{g\mu_{0}\mu_{B}}$) is half of that of the single-spin tunneling ($2|J|S/{g\mu_{0}\mu_{B}}$), which is analogous to the relationship between the magnetic flux quantum in superconductor ($h/2e$) and common metal ($h/e$).