Evidence for time-reversal symmetry breaking and glassy dynamics in superconducting (La,Pr,Sm)3Ni2O7 films
arXiv:2508.16412
Abstract
Superconductivity and magnetism are generally distinct and competing orders, characterized by different broken symmetries and order parameters. Although they may coexist in some correlated systems, whether and how these orders can become inherently intertwined in unconventional high-transition-temperature (high-Tc) superconductors remains a central open question. Here, we report time-reversal symmetry (TRS) breaking and glassy dynamics in the superconducting state of nickelate (La,Pr,Sm)3Ni2O7 films. Magnetoresistance hysteresis and zero-field non-reciprocal charge transport, complementary evidence for broken TRS, are observed in the superconducting state, while absent in the normal state. Within the superconducting transition regime, logarithmically slow resistance relaxations following magnetic-field perturbations provide strong evidence for glassy dynamics. Remarkably, the reproducible temperature hierarchy across multiple films reveals that these novel phenomena emerge concurrently with developing superconducting phase coherence, preceding the zero-resistance state. Consistently, scanning superconducting quantum interference device (sSQUID) microscopy directly resolves the zero-field magnetic-flux patterns indicative of spontaneous TRS breaking, which emerge simultaneously with local superconducting diamagnetism and phase stiffness. Our observations suggest a frustrated multicomponent superconducting order parameter in the nickelate films, whose internal relative phases may carry TRS-breaking chirality and freeze into a textured phase glass. Collectively, our findings identify a distinctive form of superconductivity in which internal phase degrees of freedom may support additional broken symmetries and glassy order, offering a new perspective on intertwined ordering phenomena in unconventional high-Tc superconductors.