Dynamic heterogeneity in the self-induced spin glass state of elemental neodymium

TL;DR

This study reveals dynamic heterogeneity in the spin glass state of elemental neodymium, showing coexistence of slow and fast magnetic dynamics and the influence of local length scales on aging, using advanced microscopy and simulations.

Contribution

It demonstrates the presence of dynamic heterogeneity and metastable periodicities in neodymium's spin glass state, linking microscopic magnetic patterns to glassy behavior.

Findings

Coexistence of slow and fast magnetic dynamics.

Metastable periodicities imprinted by zero-field cooling.

Thermal reinitialization of aging states.

Abstract

Spin glasses are magnetic materials exhibiting numerous magnetization patterns, that randomly vary both in real space and in time. To date, it is still not well understood what the nature of these spatiotemporal dynamics is, namely if they are completely random or if there are links between given time and length scales. Here we show the ubiquitous behavior of dynamic heterogeneity in the self-induced spin glass state of elemental neodymium. We used spin-polarized scanning tunneling microscopy in combination with atomistic spin dynamics simulations to image the locally ordered magnetic patterns in the glass state, and tracked the induced spatiotemporal dynamics in response to external perturbations. We observed that the real space magnetization exhibited a coexistence of slow and fast dynamics reminiscent of dynamic heterogeneity in structural glasses. Furthermore, we found that zero-field cooling imprints a specific set of metastable periodicities into the spin glass, which evolved during aging and could be thermally reinitialized. These results demonstrate the importance of local length scales for the understanding of aging dynamics in spin glasses and provide a link to the more general picture of true glasses.