Ignition and Propagation of Magnetic Avalanches in Mn$_{12}$-Acetate: the effect of quantum tunneling

TL;DR

This study investigates how quantum tunneling influences the ignition and spread of magnetic avalanches in Mn$_{12}$-acetate, revealing threshold temperatures and resonant effects that enhance understanding of magnetic dynamics in molecular magnets.

Contribution

It demonstrates the role of thermally assisted quantum tunneling in magnetic avalanche ignition and propagation, with local measurements confirming resonant effects at specific magnetic fields.

Findings

Avalanches trigger at a threshold temperature with minima at resonant fields.

Resonant magnetic fields significantly affect avalanche velocity.

Quantum tunneling plays a crucial role in avalanche dynamics.

Abstract

Using a wire heater to ignite magnetic avalanches in fixed magnetic field applied along the easy axis of single crystals of the molecular magnet Mn$_{12}$-acetate, we report fast local measurements of the temperature and time-resolved measurements of the local magnetization as a function of magnetic field. In addition to confirming maxima in the velocity of propagation, we find that avalanches trigger at a threshold temperature which exhibits pronounced minima at resonant magnetic fields, demonstrating that thermally assisted quantum tunneling plays an important role in the ignition as well as the propagation of magnetic avalanches in molecular magnets.