Title :
Oxidation and reduction during fabrication of high quality Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/ superconducting thin films
Author :
Mao, S.N. ; Xi, X.X. ; Bhattacharya, S. ; Li, Q. ; Peng, J.L. ; Mao, J. ; Wu, D.H. ; Anlage, S.M. ; Greene, R.L. ; Venkatesan, T.
Author_Institution :
Dept. of Phys., Maryland Univ., College Park, MD, USA
fDate :
3/1/1993 12:00:00 AM
Abstract :
Using pulsed-laser deposition and N/sub 2/O reactive gas, the authors have fabricated very high quality c-axis n-type Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/ (NCCO) oxide epitaxial superconducting thin films on different substrates. The film shows a superconducting transition temperature T/sub c/ (R=0 Omega ) of 22.4 K and a transition width of 0.2 K from AC susceptibility measurements. The critical current density J/sub c/ is 8*10/sup 5/ A/cm/sup 2/ at 4.2 K in zero magnetic field. The microwave surface resistance measured at 9.6 GHz shows a value of 3 m Omega at 4.2 K in 500-nm-thick NCCO film, the best result reported so far for NCCO thin films. The oxygen deficiency is necessary to achieve the superconductivity in NCCO, and the oxygen reduction during and after film deposition is critical. The oxidation and reduction processes are studied systematically for various substrate temperatures, atmospheres, and annealing durations.<>
Keywords :
cerium compounds; critical current density (superconductivity); high-temperature superconductors; neodymium compounds; oxidation; pulsed laser deposition; reduction (chemical); superconducting epitaxial layers; superconducting transition temperature; 22.4 K; 4.2 K; 500 nm; 9.6 GHz; AC susceptibility measurements; N/sub 2/O reactive gas; Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/; annealing durations; atmospheres; critical current density; epitaxial superconducting thin films; fabrication; high quality Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/ superconducting thin films; microwave surface resistance; oxygen deficiency; pulsed-laser deposition; reduction; substrate temperatures; substrates; superconducting transition temperature; transition width; very high quality c-axis n-type Nd/sub 1.85/Ce/sub 0.15/CuO/sub 4-y/; zero magnetic field; Electrical resistance measurement; Fabrication; Magnetic field measurement; Neodymium; Oxidation; Substrates; Superconducting films; Superconducting thin films; Superconducting transition temperature; Surface resistance;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
