B Maiorov et al 2009 Supercond. Sci. Technol. 22 125011 doi:10.1088/0953-2048/22/12/125011
B Maiorov1, S A Baily1,2, Y Kohama2,3, H Hiramatsu4, L Civale1, M Hirano4,5 and H Hosono4,5
Show affiliationsWe present measurements of the field and angular dependence of the critical current density (Jc) and melting line made using transport and magnetization techniques for SrFe1.8Co0.2As2 (nominal composition) biaxially oriented films. At high magnetic fields the angular dependence of the melting line and Jc (for μ0H>2 T) can be successfully scaled using an anisotropic scaling with γ = 2, indicating a random-point-like pinning contribution. At lower fields, angular and field Jc dependences strongly depend on the magnetic field history. We find a hysteretic behaviour of Jc with H with higher Jc in the descending branch, similar to that attributed to magnetic pinning and granularity effects. Furthermore this allows us to tune Jc(Θ) such that a Jc peak along the c axis can be enhanced up to 30%. The low values of Jc measured suggest that granularity depresses Jc but does not rule out the possibility of dilute magnetic pinning.
74.25.Qt Vortex lattices, flux pinning, flux creep
74.25.Op Mixed states, critical fields, and surface sheaths
74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
Issue 12 (December 2009)
Received 5 June 2009, in final form 11 September 2009
Published 23 October 2009
B Maiorov et al 2009 Supercond. Sci. Technol. 22 125011
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