Thermal decoupling in high-Tc cuprate superconductors

Abstract

Abstract In unconventional high-Tc cuprate superconductors, the intricate interplay between the non-ergodic bad metal 1,2 and the strange metal state 3 has remained enigmatic. Herein, we unravel this mystery using ab initio molecular dynamics (AIMD) simulations coupled with the temperature-dependent effective potential (TDEP) method. Our investigation, centered on YBa2Cu3O7 (YBCO), provides the first simulation report on the B1g phonon anomaly 4,5, unveiling profound thermal decoupling induced by the bond weakening between the Ba atom and CuO2 plane. Notably, this decoupling emerges as a pivotal underpinning behind several puzzling phenomena in high-Tc superconductivity. Our results indicate that the effective temperature on the BaO plane deviates from that of the CuO2 plane at low temperatures. Furthermore, we delineate the correlation between thermal decoupling and the Planckian dissipation, rigorously and quantitatively revealing a profound connection between linear-T resistivity, Uemura plots, and superconducting domes, which are known to be the most important unsolved mysteries of high-Tc superconductivity. Our discoveries offer a revolutionary perspective on high-Tc superconductivity, suggesting the potential for a transformative shift in our comprehension. Furthermore, they suggest that the autonomous emergence of low-temperature layers within materials has the potential to revolutionize industrial thermal management challenges.