Thin-film-like BSCCO single crystals made by mechanical exfoliation

Abstract

Mechanical exfoliation has been proven to be an effective technique for producing one to several layers of strong anisotropic materials such as graphite, NbSe2 and Bi2Te3. Using this technique, thin-film-like BSCCO (Bi2Sr2CaCu2O8+δ and Bi2Sr2Ca2Cu3O8+δ) single crystals with typical thickness of a few to a few tens of nanometres are successfully produced. The thinnest crystal is only 0.5 unit cell in the c-axis. The measured resistivity–temperature properties of a 30nm-thick crystal show excellent superconductivity. It is observed that the topology of exfoliated thin-film-like single crystal can copy the structure of the substrate in AFM and profilometer measurements. With the aid of a dual-beam Focused Ion Beam, the interface between the thin-film-like BSCCO single crystal and a step-structured substrate is visible in a cross-section view, which shows that there is a gap between the step substrate and the thin-film-like single crystal. The gap size is sensitive to the thickness of the thin-film-like BSCCO single crystal as well as the structure of the substrate.