Meissner response of a bulk superconductor with an embedded sheet of reduced penetration depth

Abstract

We calculate the change in susceptibility resulting from a thin sheet with reduced penetration depth embedded perpendicular to the surface of an isotropic superconductor, in a geometry applicable to scanning Superconducting QUantum Interference Device (SQUID) microscopy, by numerically solving Maxwell's and London's equations using the finite element method. The predicted stripes in susceptibility agree well in shape with the observations of Kalisky et al. of enhanced susceptibility above twin planes in the underdoped pnictide superconductor Ba(Fe1-xCox)2As2 (Ba-122). By comparing the predicted stripe amplitudes with experiment and using the London relation between penetration depth and superfluid density, we estimate the enhanced Cooper pair density on the twin planes, and the barrier force for a vortex to cross a twin plane. Fits to the observed temperature dependence of the stripe amplitude suggest that the twin planes have a higher critical temperature than the bulk, although stripes are not observed above the bulk critical temperature.

16 pages, 9 figures

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Cited by in corpus (9)

• Fundamental studies of superconductors using scanning magnetic imaging
• Suppression of Superconductivity by Twin Boundaries in FeSe
• Behavior of vortices near twin boundaries in underdoped $Ba(F{e}_{1-x}C{o}_x{)}_{2}A{s}_2$
• Enhanced superfluid density on twin boundaries in Ba(Fe1-xCox)2As2
• Universality of modulation length (and time) exponents
• Diamagnetic Vortex Barrier Stripes in Underdoped $BaF{e}_2(A{s}_{1-x}{P}_x{)}_2$
• Meissner response of superconductors with inhomogeneous penetration depths
• The magnetic penetration depth influenced by the proximity to the surface
• Penetration of the magnetic field into the twinning plane in the type I and II superconductors