Vortex pinning in artificially layered Ba(Fe, Co)2As2 film. (June 2018)

• Record Type: Journal Article
• Authors: Oh, M.J.; Lee, Jongmin; Seo, Sehun; Yoon, Sejun; Seo, M.S.; Park, S.Y.; Kim, Ho-Sup; Ha, Dong-Woo; Lee, Sanghan; Jo, Youn Jung
• Is Part Of: Cryogenics. Volume 92(2018)
• Page Start: 1
• Page End: 4
• Publication Date: 2018-06
• Subjects: Superconducting film -- Artificially layered film -- Vortex pinning scaling; Low temperature engineering -- Periodicals; Low temperature research -- Periodicals; 536.56
• DOI: 10.1016/j.cryogenics.2018.03.006
• Languages: English
• ISSNs: 0011-2275

Abstract

Highlights: Co-doped BaFe2 As2 and pure BaFe2 As2 layers are deposited periodically. The Δl-pinning dominance shows that the pure Ba122 layer is the non-superconductor. The dominant geometry of pin is changed as a direction of magnetic field. The 3-D superconductor originated by its long correlation length is found. Abstract: Static high critical current densities ( J c ) > 1 MA/cm 2 with magnetic field parallel or perpendicular to c -axis were realized in Co-doped/undoped multilayerd BaFe2 As2 films. We made a current bridge by FIB to allow precise measurements, and confirmed that the boundary quality using FIB was considerably better than the quality achieved using a laser. The presence of a high in-plane J c suggested the existence of c -axis correlated vortex pinning centers. To clarify the relationship between the J c performance and superstructures, we investigated the magnetic flux pinning mechanism using scaling theory of the volume pinning force F p ( H ). The J c ( H ) curves, F p / F p, max vs. h = H / H irr curves, and parameters p and q depended on the characteristics of the flux pinning mechanism. It was found that the dominant pinning mechanism of Co-doped/undoped multilayerd BaFe2 As2 films was Δl-pinning and the inserted undoped BaFe2 As2 layers remained non-superconducting. The dominant pin geometry varied when the magnetic field direction changed. It was concluded that the artificially layered BaFe2 As2 film is a 3-D superconductor due to its long correlation length compared to the thickness of the non-superconducting layer.