Research On LMO And LMO:MGO Composit Thin Films Using RF Sputtering

Due to its low cost, high current carrying capacity, good mechanical strength and advantages of mass production, the second generation high temperature superconducting(HTS) tape, which is typically represented by YBa2Cu3O7-X(YBCO), can be widely used in areas such as energy storage, power transmission and strong magnetic fields. High quality template layer is crucial to get high performance YBCO superconducting thin film. In this thesis, IBAD technology was applied and LMO films was fabricated as the template layer for YBCO. In order to improve the performance of YBCO under the magnetic field, try using the LMO: MgO film was prepared instead of LMO films as new template layer. By adjusting the process parameters of radio frequency magnetron sputtering, the growth mechanism of LaMnO3(LMO) and LMO:MgO film was systematically studied. And the following aspects was included:1. The growth condition of LMO thin film with RF sputtering. growth window of LMO template layer has been researched by adjusting process parameters such as deposition temperature, sputtering power, and argon pressure. With the optimized process condition, the full width at half- maximum(FWHM) values of out-of-plane and in-plane texture of LMO are 3?and 5.4?, respectively. The surface roughness(Rrms) of the thin film is only 2 nm. So a high quality LMO template layer for YBCO superconducting layer. Meanwhile, the growth mechanism of LMO thin film has been analyzed.2. The impact of the surface roughness of LMO thin film on the structure and performance of YBCO superconducting thin film. The variation of YBCO thin film structure and performance has been studied by depositing YBCO thin films on LMO template layer with different root mean square surface roughness(Rrms). The result showed that as the Rrms of LMO thin films reduced from 7 nm to 1.3 nm, the structure of YBCO was improved and the critical current density of YBCO arises from 1 MA/cm2 to 2.4 MA/cm2.3. The growth of LMO:MgO composite film. According to the process condition of LMO film, the LMO:MgO composite film was prepared with further optimized process conditions. And the growth condition of LMO:MgO composite thin film is also analyzed. LMO:MgO composite thin films had been grown separately on single crystal LaAlO3 substrates and IBAD-MgO buffered Hastelloy tape. LMO:MgO composite films had been obtained with clear phase boundaries.4. Deposition of YBCO superconducting thin films on LMO film and LMO:MgO composite film. With similar deposition parameters, YBCO thin films were deposited on two kinds of template layers. The performance under magnetic field has been compared. The results showed that although the crystallinity and structure of YBCO are similar, the critical current of YBCO thin films grown on LMO:MgO composite film degenerated much slower with increasing magnetic field.