Growth of Strongly Biaxially Aligned MgB2 Thin Films on Sapphire by Post-annealing of Amorphous Precursors

摘要

MgB2 thin films were cold-grown on sapphire substrates by pulsed laserdeposition (PLD), followed by post-annealing in mixed, reducing gas, Mg-rich,Zr gettered, environments. The films had Tcs in the range 29 K to 34 K, Jcs(20K, H=0) in the range 30 kA/cm2 to 300 kA/cm2, and irreversibility fields at20 K of 4 T to 6.2 T. An inverse correlation was found between Tc andirreversibility field. The films had grain sizes of 0.1-1 micron and a strongbiaxial alignment was observed in the 950C annealed film.