【摘要】 采用直流磁控溅射和在纯氩气中后热处理的方法 ,在LaAlO3 (0 0 1 )衬底上生长出厚度小于 1 0 0nm的Tl2 Ba2 CaCu2 Ox(Tl 2 2 1 2 )超导薄膜 .在 77K和零磁场下 ,1 0 0nm厚的薄膜具有1 0 5 .3K的超导转变温度和 2 .33× 1 0 6A/cm2 的临界电流密度 .这些值与较厚的Tl 2 2 1 2薄膜的最好值相符 .30nm厚的薄膜仍具有大于 1 0 0K的转变温度 ,并具有光滑致密的表面形貌和外延生长的晶体结构 .2 0nm厚的薄膜仍显示出正常态的金属行为和充分的超导转变 .当厚度小于 2 0nm时 ,薄膜的表面形貌和超导电性明显变坏 ,6nm厚的薄膜在 1 5K低温下 ,未发现超导转变 .从这个意义上看 ,2 0nm为我们所研究的Tl 2 2 1 2薄膜的临界厚度 .更多还原

【Abstract】 Very thin Tl-2Ba-2CaCu-2O-x superconducting films with thickness less than 100nm have been fabricated on LaAlO-3 (001) substrates using dc magnetron sputtering and post-annealing process in pure argon. For a 100 nm thick film, T-c and J-c (77K, 0T) show the values of 105.3K and 2.33×106A/cm2, respectively, which are very close to the optimal value of thicker Tl-2212 films. A 30nm thick film with T-c>100K show smooth surface morphology and high quality epitaxy. A 20nm thick film revealed full transition to superconductivity, The superconductivity and surface morphology deteriorated rapidly as the film thickness below 20nm. A 6nm thick Tl-2212 film was not found to be superconducting at temperature down to 15K. In our experiments the critical film thickness leading to degradation of the superconducting properties was 20nm.更多还原