Temperature Chaos in Spin Glasses

The problem of temperature chaos in spin glasses, which predicts the sensitivity of the spin configuration to the external temperature perturbations in equilibrium, has been formalized, debated and studied for nearly four decades. Although its theoretical existence has been proved, its physical observation remains elusive due to the non-equilibrium nature of a real spin glass system. In our study, by separating and comparing two length scales, the correlation length and the chaos length and by utilizing a high-quality CuMn single crystal sample, we traced the dynamics of spin glass with and without external temperature perturbations. Our experimental results strongly suggest the presence of temperature chaos in a real spin glass system with the calibrated chaos exponent matching theoretical predictions.