Fabrication And Properties Of Oriented Ybco Thin Film By Pulsed Laser Deposition

YBa₂Cu₃O_7-x?YBCO? high temperature superconducting thin film have been attracted much attention due to its high critical current density, high critical transition temperature and its excellent current-carring capacity. As well it have extensive application prospect in high temperature superconducting electric devices. The fabraication of high quality and property YBCO thin film is the foundation of the superconducting electronics application. YBCO films have strong anisotropy, its superconductivity is closely related with its orientation. And the practical application are based on the superconducting films with c-axis and a-axis orientation.The c-axis orientation films always used to the superconducting device and the coated conductor, a-axis orientation films are used to the study of the superconducting mechanism and the prepare of Josephson junction. But it's difficult to get YBCO films with single orientation.In this paper, we intend to use the pulsed laser deposition to control the orientation of YBCO films. obtain an epitaxial film with single orientation.First, deposite a series of YBCO thin films on Lanthanum aluminate?LAO? single crystal substrates under different parameter. The study found that deposited temperature and pressure are the mean factors effect the orientation of YBCO films. It's easy to grow a-axis orientation films under low temperature and high pressure, grow c-axis orientation films under high temperature and low pressure,in the experiment, we have got a-axis orientation films under 725 ? and 70Pa; got c-axis orientation films under 850? and 10Pa, its critical transition temperature was about 67K.Secondly, the introduction of argon as a heat transfer medium can improve the actual temperature is beneficial to the diffusion of oxygen atoms, thus increasing the critical transition temperature. The results show that the critical transition temperature of YBCO thin film is increased to 88.57K under the condition of the deposition temperature of 850 ? and the total pressure is 30Pa,which is greatly improved compared with that without argon. we try to prepare the multilayer structure YBCO?c?/YBCO?a?/YBCO?c? on LAO single crystal substrate,its bottom and top layer are c-axis orientation growth, inter layer is a-axis orientation. It is shown that the epitaxial junction has good orientation and laid the foundation for the preparation of superconducting electronic devices based on Josephson junction.