A significant advancement in understanding spin glass physics has been made, as researchers have mathematically proven a connection between two perplexing phenomena: reentrance and temperature chaos. This groundbreaking work was carried out by a team from Science Tokyo and Tohoku University, marking the first time such a link has been rigorously established.
The study, published in the journal Physical Review E on October 22, 2025, extends the Edwards-Anderson model to incorporate correlated disorder. The team demonstrated that the presence of reentrance in the model implies the existence of temperature chaos, enhancing the understanding of disordered systems.
Spin glasses are unique materials characterized by atomic “spins” that align randomly, differing from the orderly arrangement found in standard magnets. This randomness can persist over extended periods, leading to unusual physical properties not observable in other systems. The Edwards-Anderson model is frequently employed by physicists to simulate the interactions of spins more accurately than the traditional mean-field model.
Through numerical studies, researchers have identified two counterintuitive phenomena within the Edwards-Anderson model: reentrant transitions and temperature chaos. In a reentrant transition, lowering the temperature results in a decrease in the system”s order, contrary to typical expectations. This phenomenon has been observed at the interfaces between ferromagnetic and spin glass or paramagnetic phases across various dimensions. Conversely, temperature chaos refers to a situation where even minimal temperature alterations can drastically restructure the material”s internal spin configuration.
The research team, led by Specially-appointed Professor Hidetoshi Nishimori, found that when temperature chaos is absent, the boundary separating ferromagnetic and spin glass states remains straight and non-reentrant. However, if this boundary bends back on itself, indicating reentrance, temperature chaos is present.
Nishimori remarked, “Our study establishes a highly nontrivial mathematical relationship between two seemingly unrelated physical phenomena observed in different regions of the phase diagram.” This research represents a significant progression in comprehending the Edwards-Anderson model through precise analytical methods, revealing an unexpected correlation between temperature chaos and reentrance.
The team also explored the implications of replica symmetry breaking, a phenomenon where two identical systems exhibit different behaviors. They discovered that under certain conditions in the Edwards-Anderson model, the magnetization distribution aligns with the distribution of replica overlap along the Nishimori line. This suggests that macroscopic properties like magnetization can vary between measurements, underscoring the influence of disorder and correlation on the system”s collective dynamics.
This discovery holds promise for advancing applications in fields like machine learning and quantum technologies, where managing disorder and errors is essential. Nishimori concluded, “This work pioneers a new pathway toward clarifying how complex behaviors in disordered systems emerge. Understanding spin glasses extends beyond magnetism, impacting materials science, Bayesian inference, optimization challenges, and error correction in quantum computing.”
