Determination of critical current density and effective depth of flux-pinning wells in anisotropic platelet-shaped superconductors

Abstract

The magnetic moment M and the normalized creep rate S of an anisotropic platelet-shaped superconductor in the transverse magnetic field H are analyzed theoretically. The emphasis is given to the case in which angular dependences of the critical current density jc and the effective depth of a flux-pinning well, U0, have peaks at θ=0 where θ is the angle between the magnetic induction B and the normal to the plane of the platelet. The analysis shows that, strictly speaking, the width of a magnetic hysteresis loop and (1/S) are proportional not to jc(H) and U0(H), respectively, but to more complex quantities, even though H exceeds considerably the self-fields of the critical currents in the sample. The manifestation of this result is the nonmonotonic H dependences of M and S for monotonically decreasing jc(|B|), U0(|B|). A method for the reconstruction of jc and U0 from experimental data on M and S is proposed. The obtained results must be taken into account when determining jc and U0 in high-Tc superconductors with extended defects.

Source-reported materials — not catalogue approval

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