Interplay between aging and rejuvenation in spin glasses

TL;DR

This study investigates how aging and rejuvenation processes interact in spin glasses, revealing that rejuvenation, not cumulative aging, explains differences in experimental aging behaviors.

Contribution

It demonstrates that rejuvenation effects dominate over cumulative aging in spin glasses, impacting how aging protocols are interpreted.

Findings

Rejuvenation explains discrepancies in aging growth rates.

Finite cooling rate experiments differ from quench protocols.

Rejuvenation, not cumulative aging, is the primary factor.

Abstract

Aging in a single crystal spin glass ($\mathrm{Cu}_{0.92}\mathrm{Mn}_{0.08}$) has been measured using ac susceptibility techniques over a temperature range of $0.3 - 0.8 \, T_g$. In these studies, traditional aging experiments (or ``quench'' aging protocols) are compared to aging curves constructed from finite-cooling-rate curves. By comparing the growth rates of spin glass order between the two types of aging curves, it is determined that quantitative comparisons between protocols which are taken by quenching and protocols using a finite cooling rate are not possible without a deeper understanding of the interplay between aging and rejuvenation. We then demonstrate that the data presented indicate that rejuvenation, rather than cumulative aging, is the cause for the discrepancies between the two growth rates.