We test the fluctuation-dissipation relation (FDR) in spin ice materials Dy2Ti2O7 and Ho2Ti2O7 by measuring both the magnetic noise and the out-of-phase part of the susceptibility and comparing their ratio. We show that it is satisfied at temperatures well into the non-ergodic region below 600 mK, indicating local equilibrium. In both materials, below 400 mK, low frequency violations develop, showing an excess of noise as in spin glasses, with a frequency threshold of 0.1 Hz. New relaxation pathways and aging properties are unveiled in this frequency range in the ac susceptibility. The FDR remains valid at higher frequencies down to 150 mK.
@article{arxiv.2410.12548,
title = {Satisfaction and Violation of the Fluctuation-Dissipation Relation in spin ice materials},
author = {F. Morineau and V. Cathelin and P. C. W. Holdsworth and S. R. Giblin and G. Balakhrishnan and K. Matsuhira and C. Paulsen and E. Lhotel},
journal= {arXiv preprint arXiv:2410.12548},
year = {2025}
}