Cation exchange: A scheme for synthesis of mercury-based high-temperature superconducting epitaxial thin films

Abstract

A cation-exchange process has been developed for growth of high-quality epitaxial thin films of highly volatile mercury-based high-temperature superconductors. By selecting epitaxial precursor matrices of TlyBa2CaCu2Ox (y=1,2) and annealing them in Hg vapor, c-axis-oriented epitaxial HgBa2CaCu2O6+δ thin films with superior quality were formed through Tl and Hg-cation exchange. At 110 K, these films can carry supercurrent density close to 1 MA/cm2 which is nearly an order of magnitude higher than the best reported previously. This cation-exchange technique also provides a general scheme for synthesis of other volatile compounds with predesigned structure and composition.