Growth of highly oriented (Hg, Pb)-based superconducting thin films on LaA103 substrates by pulsed-laser ablation

摘要

The discovery of the homologous series of HgBa2Can-1CunB02n+2+d (Hg-12(n - l)n, n = l, 2, 3, ...) has attracted considerable attention since they raised the superconducting critical temperature, T, to record values of 134 K at ambient pressure and 164 K at 30GPa pressure [1, 2]. Thus high-quality Hg-based thin films are desirable from the view points of both basic research and technological applications. The main difficulty in synthesizing such thin films is the high volatility of Hg and Hg-based compounds. Following the so far most successful way to overcome this volatility problem [3-9], which is similar to that used for preparing Hg-based ceramics, we fabricated precursor films first and then annealed them in a controlled Hg atmosphere. Furthermore, as several studies demonstrated that partly substitution of lead for mercury could prevent rapid evaporation of mercury to promote the formation of the superconducting phase and that proper Pb doping could enhance the Tc of Hg-based compounds [10-12], we decided to use a superconducting Hgo.7Pbo.3Ba2Ca2Cu3O.-c target in the fabrication. In this letter we discuss the details of the fabrication and the films' properties.