Critical current density and grain boundary property of BaFe2(As,P)2 thin films

• Jc and grain boundary property of BaFe2(As,P)2 thin films were investigated.
• We found a correlation of Jc with the Fe/Ba composition ratio.
• A very large Jc of 1.2 × 107 A/cm2 was observed with a Fe rich thin film.
• A grain boundary junction having a misorientation angle of 24° was fabricated.
• Jc across the grain boundary (θGB = 24°) recorded 106 A/cm2.

We have investigated the critical current density (Jc) and the grain boundary property of BaFe2(As,P)2 thin films grown on MgO single crystal or bicrystal substrates by molecular beam epitaxy. We found a strong correlation between Jc and the Fe/Ba composition ratio, and a very large self-field Jc of 1.2 × 107 A/cm2 at 4.2 K with a thin film for which the Fe/Ba ratio was 2.4. A grain boundary junction was fabricated by growing a thin film on a MgO bicrystal substrate having a misorientation angle of 24°. The inter-grain Jc at 4.0 K recorded 106 A/cm2, which is higher than that of YBa2Cu3Oy. These results demonstrate the high potential of BaFe2(As,P)2 in practical applications and indicate that the necessary condition for in-plane alignment is less severe than YBa2Cu3Oy.