Memory interference effects in spin glasses

TL;DR

This paper investigates how spin glasses retain and erase thermal memory during cooling and heating, comparing experimental observations with theoretical models to understand the underlying interference effects.

Contribution

It provides experimental evidence of memory effects and interference phenomena in spin glasses, contrasting hierarchical and droplet models to explain these behaviors.

Findings

Memory is retained during cooling and can be recovered upon reheating.

Heating above the aging temperature erases the memory.

Long waiting times at lower temperatures can erase higher-temperature memories.

Abstract

When a spin glass is cooled down, a memory of the cooling process is imprinted in the spin structure. This memory can be disclosed in a continuous heating measurement of the ac-susceptibility. E.g., if a continuous cooling process is intermittently halted during a certain aging time at one or two intermediate temperatures, the trace of the previous stop(s) is recovered when the sample is continuously re-heated [1]. However, heating the sample above the aging temperature, but keeping it below Tg, erases the memory of the thermal history at lower temperatures. We also show that a memory imprinted at a higher temperature can be erased by waiting a long enough time at a lower temperature. Predictions from two complementary spin glass descriptions, a hierarchical phase space model and a real space droplet picture are contested with these memory phenomena and interference effects. [1] K. Jonason, E. Vincent, J. Hammann, J. P. Bouchaud and P. Nordblad, Phys. Rev. Lett. 31, 3243 (1998).