Dynamic behavior of magnetic avalanches in the spin-ice compound Dy$_2$Ti$_2$O$_7$

TL;DR

This study investigates the slow, field-dependent magnetization avalanches in Dy$_2$Ti$_2$O$_7$ spin ice, revealing a possible link to monopole dynamics and emphasizing the influence of initial conditions on avalanche behavior.

Contribution

It provides a detailed experimental analysis of magnetization avalanches in Dy$_2$Ti$_2$O$_7$, highlighting their slow dynamics and potential connection to magnetic monopoles, which is a novel insight in spin ice physics.

Findings

Avalanches occur after a ~500 ms delay and complete in a few hundred milliseconds.

Avalanche fields are reproducible for a given direction but depend on initial magnetization.

Avalanche propagation may be influenced by monopole motion.

Abstract

Avalanches of the magnetization, that is to say an abrupt reversal of the magnetization at a given field, have been previously reported in the spin-ice compound Dy$_{2}$Ti$_{2}$O$_{7}$. This out-of-equilibrium process, induced by magneto-thermal heating, is quite usual in low temperature magnetization studies. A key point is to determine the physical origin of the avalanche process. In particular, in spin-ice compounds, the origin of the avalanches might be related to the monopole physics inherent to the system. We have performed a detailed study of the avalanche phenomena in three single crystals, with the field oriented along the [111] direction, perpendicular to [111] and along the [100] directions. We have measured the changing magnetization during the avalanches and conclude that avalanches in spin ice are quite slow compared to the avalanches reported in other systems such as molecular magnets. Our measurements show that the avalanches trigger after a delay of about 500 ms and that the reversal of the magnetization then occurs in a few hundreds of milliseconds. These features suggest an unusual propagation of the reversal, which might be due to the monopole motion. The avalanche fields seem to be reproducible in a given direction for different samples, but they strongly depend on the initial state of magnetization and on how the initial state was achieved.