Superconducting Fluctuation Driven Quantum Transport in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ Thin Films

Abstract

Superconducting fluctuations (SF), arising from Cooper-pair-driven interactions and electron-electron interactions within the transition regime, can dominate the magnetoconductance (MC) of superconducting thin films near their transition temperature. In some systems, this fluctuation-dominated regime is preceded by a narrow window in which quantum interference effects are manifested as weak antilocalization (WAL) or weak localization (WL). Here, we report magnetotransport measurements on thin films of the high-temperature superconductor Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ (BSCCO) that establish SF as the dominant mechanism governing MC across the transition regime. In the narrow temperature window well above $T_c$ where SF does not exist, a cusp in MC can be attributed to WAL-like signature well described by the Hikami--Larkin--Nagaoka (HLN) framework. Closer to the transition ($T_{BKT}$), we observe signatures consistent with Berezinskii--Kosterlitz--Thouless (BKT) correlations, underscoring that the dominant physics is set by collective, pairing-driven behavior rather than single-particle quantum interference. Measurements on non-superconducting control samples show no WAL-like features, indicating that the WAL over narrow temperature window, emerges only in conjunction with superconducting fluctuations. Hall measurements further reveal a concomitant sign reversal of the dominant carrier response, pointing to a substantial reorganization of transverse transport coincident with the onset of superconductivity. Together, these observations establish that magnetotransport in BSCCO thin film.

arXiv commentThe Central Inferences and Figures of the paper have changed significantly compared to v1 of arXiv: 2511.00803