Enhancement of the critical current density of MgB2 thick films by Ag- and Cu-impurity layers

✍ Scribed by M. Ranot; W.K. Seong; S.-G. Jung; N.H. Lee; W.N. Kang; J.H. Joo; Y. Zhao; S.X. Dou

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 590 KB
• Volume: 469
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2009.05.223

✦ Synopsis

We report on Ag and Cu doping in MgB 2 thick films using amorphous Ag-and Cu-impurity layers with various thicknesses, 4, 8, 16, and 32 nm. Firstly, Ag-and Cu-impurity layers were deposited on Al 2 O 3 (0 0 0 1) substrates at room temperature by using pulsed laser deposition system. Subsequently MgB 2 films were grown on the top of Ag or Cu/Al 2 O 3 substrates at 560 and 600 °C by using hybrid physical-chemical vapor deposition. The effect of Ag and Cu doping as well as growth temperature on the microstructure and critical current density (J c ) of MgB 2 films were investigated. It was found that both of Ag/Cu doping and low growth temperature can significantly enhance J c without suppression of T c . The increase in J c results from improved grain connectivity and strong flux pinning by high density of grain boundaries and other types of defects introduced by Ag-or Cu-impurity layers.