Magneto-optical studies of flux penetration in super-hard Nb wire
We present a study of the magnetic response of type-II superconductivity in the extreme pinning limit, where screening currents within an order of magnitude of the Ginzburg-Landau depairing critical current density develop upon the application of a magnetic field. We show that this 'super-hard' limit is realized in highly disordered, cold drawn, Nb wire whose magnetization response is characterized by a cascade of Meissner-like phases, each terminated by a catastrophic collapse of the magnetization. Direct magneto-optic measurements of the flux penetration depth in the virgin magnetization branch are in excellent agreement with the exponential model in which JC(B) = Jco exp(-B / Bo). where Jco ∼ 5 × 106 A cm-2 for Nb. The implications for the fundamental limiting hardness of a superconductor are discussed. © 2005 IOP Publishing Ltd.
Publication Source (Journal or Book title)
Superconductor Science and Technology
Young, D., Moldovan, M., Adams, P., & Prozorov, R. (2005). Magneto-optical studies of flux penetration in super-hard Nb wire. Superconductor Science and Technology, 18 (5), 776-779. https://doi.org/10.1088/0953-2048/18/5/034