High Critical Current Density 4 MA/cm²in Co-Doped BaFe₂As₂Epitaxial Films Grown on (La,Sr)(Al,Ta)O₃Substrates without Buffer Layers

Abstract

High critical current densities J c of 4 MA/cm 2 at 4 K were obtained in Co-doped BaFe 2 As 2 (BaFe 2 As 2 :Co) epitaxial films grown directly on (La, Sr)(Al, Ta)O 3 substrates by pulsed laser deposition. Use of a highly pure target and improvement of film homogeneity were the critical factors to achieve the high J c . The improved BaFe 2 As 2 :Co epitaxial films contained almost no Fe impurity and showed high crystallinity (crystallite tilt angle ∆ω = 0.5 ° and twist angle ∆φ = 0.5 °) and a sharp superconducting transition with a width of 1.1 K. It is considered that these improvements resulted in the enhanced superconducting properties comparable to those of single crystals. *

Transport and magnetic properties of Co-doped BaFe2As2epitaxial thin films grown on MgO substrate

“…The phase purity and crystallinity were quite similar to those of samples reported in Ref. 17. The obtained films were patterned in a 6.7 μm wide four-terminal and 0.1 mm wide six-terminal shape for I-V measurements, and for resistivity and Hall measurements, respectively by photolithography and Ar ion milling.…”

“…The results of our investigations using resistivity, Hall coefficient, current-voltage (I-V) characteristics, and magneto-optical imaging measurements are discussed. 8% Co-doped BaFe 2 As 2 films with thickness 220 nm were deposited on MgO(001) single-crystal substrates by laser ablation [17]. The phase purity and crystallinity were quite similar to those of samples reported in Ref.…”

Anomalous scaling behavior in a mixed-state Hall effect of a cobalt-doped BaFe2As2epitaxial film with a high critical current density over 1 MA/cmSato1, Katase2, Kang3 et al. 2013Phys. Rev. BSelf Cite17170View full textAdd to dashboardCite

“…[3] In particular, Ba(Fe 1-x Co x ) 2 As 2 (BaFe 2 As 2 :Co) epitaxial films have achieved high critical current densities (J c ) ≥ 1 MA/cm 2 , [4][5][6] and have been applied to Josephson junctions [7,8] and a superconducting quantum interference device. [9] Compared to cuprates, the properties of iron-pnictide Josephson-junction devices remain inferior due largely to their metallic characters.…”

High critical-current density with less anisotropy in BaFe2(As,P)2 epitaxial thin films: Effect of intentionally grown c-axis vortex-pinning centers

“…[6] However, as compared to BaFe 2 As 2 :Co, 122-type BaFe 2 (As 1-x P x ) 2 (BaFe 2 As 2 :P) exhibits a higher T c (~31 K) and a comparable γ. [7] In addition, it was recently reported [8] that BaFe 2 As 2 :P epitaxial films have a very high J c of 10 MA/cm 2 , which is two to three times greater than that of BaFe 2 As 2 :Co. [9,10] Unfortunately, the decay rate of J c for a BaFe 2 As 2 :P epitaxial film under a magnetic field [7] is greater than that of a BaFe 2 As 2 :Co epitaxial film. [11] This observation is attributed to the weak vortex pinning in BaFe 2 As 2 :P because an isovalent P dopant is not thought to work as an effective pinning center.…”