Bi₂Sr₂CaCu₂O₈ single crystal exfoliation, characterization, and manipulation

Bi₂Sr₂CaCu₂O₈ (BSCCO) is a high T_c cuprate superconductor whose layered crystal structure allows the study of thickness dependence of its superconducting properties down to mono-layer. We developed a process to manipulate and analyze BSCCO single crystal and bi-crystal junctions at different film thickness. First, thickness characterization was performed through profile extraction with atomic force microscopy (AFM). A transfer stage was then used to isolate individual flakes of varying thickness in order to study their magnetic response on a SQUID magnetometer. Thin films of less than 100 nm were found to maintain their superconducting properties, which can be inferred from the observation of Meissner effect on the samples. Finally, by using the transfer stage, different layers of BSCCO were rotated around the c-axis and stacked on top of each other. These manipulations enable the study of superconducting properties of bi-crystal junction as a function of the twist angle and the layer thickness.