Phonon-bottleneck enhanced magnetic hysteresis in a molecular paddle wheel complex of Ru$_2^{5+}$

TL;DR

This study investigates how phonon bottleneck effects enhance magnetic hysteresis in a ruthenium-based molecular magnet, revealing unique irreversibility features and spin dynamics at low temperatures.

Contribution

It demonstrates the role of phonon bottleneck in amplifying magnetic hysteresis and provides experimental and simulation evidence for spin reversal mechanisms in a molecular paddle-wheel complex.

Findings

Enhanced magnetic irreversibility observed in Ru₂ complex

Phonon bottleneck model explains abrupt spin reversal

Insufficient thermal coupling affects spin dynamics

Abstract

The ruthenium based molecular magnet [Ru$_2$(D(3,5-Cl$_2$Ph)F)$_4$Cl(0.5H$_2$O)$\cdotp$C$_6$H$_{14}$] (hereafter Ru$_2$) behaves as a two-level system at sufficiently low temperatures. The authors performed spin detection by means of single-crystal measurements and obtained magnetic hysteresis loops around zero bias as a function of field sweeping rate. Compared to other molecular systems, Ru$_2$ presents an enhanced irreversibility as shown by ``valleys'' of negative differential susceptibility in the hysteresis curves. Simulations based on phonon bottleneck model are in good qualitative agreement and suggest an abrupt spin reversal combined with insufficient thermal coupling between sample and cryostat phonon bath.