An Improved Procedure for Preparing Epitaxial Tl-2201 Films on Single Crystal LaAlO_3 and SrTiO_3

摘要

Epitaxial Tl-2201 films are prepared on single crystal LaAlO_3 and SrTiO_3 by thallization of thallium-free precursor films made by laser ablation. Thallization is carried out in two consecutive steps. In the first step. at 720℃, a smooth and epitaxial film is produced. The second thallization, at 820℃, improved film crystallinity and the T_c The films were characterized by X-ray diffraction and by resistance and susceptibility measurements. For a film on single crystal LaAlO_3, the FWHM of the Ω scan (0,0,10) was 0.27°.T_c was 84K while J_c reached 1.6×10~6 A/ cm~2 at 77K. A film on single crystal SrTiO_3 exhibited somewhat lower T_c (78 K) while J_c was much smaller (9.5×10~3 A/cm~2 at 70.4K).