Procedure for preparing epitaxial Tl-2201 films on single crystal LaAlO_(3)

摘要

Epitaxial Tl-2201 films are prepared by treating precursor films deposited on single crystal LaAlO_(3) by laser ablation with Tl_(2)O vapor at high temperature. Here, a procedure is described that includes thallization in two separate steps. The first thallization at 720℃ resulted in good epitaxy as well as in smooth morphology. The second thallization at 820℃ resulted in an improvement of the superconducting properties and in film crystallinity without affecting epitaxy or morphology. The films were characterized by x-ray diffraction (φ scan, Ω scan, θ-θ scan), and by resistance and susceptibility measurements. The films are tetragonal. In a typical film, the full width at half maximum of the Ω scan of the (0,0,10) reflection was 0.27°. A 5 μm wide bridge patterned in one film had a T_(c) of 84 K. The critical current density reached 1.4×10~(6) A/cm~(2) at 77 K and 1.4×10~(7) A/cm~(2) at 4.2 K.