Characterizing anomalous peaks in the resistance–temperature profile of Bi₂Sr₂CaCu₂O₈₊ _δ flakes featuring surface degeneration

Abstract This study focuses on an observed anomalous resistance peak in the temperature-dependent resistance (RT) curves of Bi 2 Sr 2 CaCu 2 O 8+ δ (BSCCO), attributed to surface degradation and pronounced electrical resistance anisotropy. Employing a standard four-point probe technique on the ab -plane, this research circumvents conventional c -axis testing limitations, enhancing the understanding of BSCCO’s electrical behavior by avoiding contact resistance and etching issues. A comprehensive three-dimensional model, developed using the finite element method, captures the strong resistive anisotropy and correlates the depth of surface degradation with the anomalous resistance peaks, explaining this phenomenon from a quantitative perspective, providing a more specific reference for future analysis of relevant signals. The fabrication process involved pre-patterning and mechanical exfoliation techniques to minimize atmospheric exposure and ensure device integrity. Despite these efforts, surface degradation impacting the superconductivity of surface layers was inevitable. The study’s experimental results, complemented by numerical modeling, reveal the intricate relationship between surface layer thickness and the anomalous resistance peak, providing an approach to gauge the extent of degradation in BSCCO devices. Moreover, it underscores the potential necessity of employing some critical techniques to avoid degradation, such as low-temperature exfoliation in other literatures where degradation signal is notably absent from RT curves. This work advances the understanding of BSCCO’s electrical properties and highlights the critical need for precise fabrication and environmental controls in developing high-temperature superconducting technologies.