MgB2 thin films with high Jc fabricated on Al tape substrates by electron beam evaporation

Abstract MgB 2 thin films on nontextured Al tape substrates were fabricated by electron beam evaporation. MgB 2 thin film with a boron buffer layer of about 3 nm thickness was also prepared. The thickness of MgB 2 thin films is 250 nm. The obtained MgB 2 thin films on Al tape substrates were boron rich in composition and c -axis oriented. The self-field J c of the MgB 2 thin film with a boron buffer layer at 10 K and 20 K are 9.45 × 10 10  A/m 2 and 4.85 × 10 10  A/m 2 , respectively. The magnetic field reduction of J c in MgB 2 thin films on Al tape substrates is smaller compared with MgB 2 wires fabricated by a powder-in-tube method and MgB 2 thin films fabricated by a hybrid physical chemical vapor deposition method. The field angular dependences of J c of MgB 2 thin films on Al tape substrates are similar to that of the MgB 2 thin film on Si, which was reported previously. This result indicates that grain boundaries act as a dominant pinning center in MgB 2 thin films on Al tape substrates.