Why an ac Magnetic Field Shifts the Irreversibility Line in Type-II Superconductors

Ernst Helmut Brandt; Grigorii P. Mikitik

doi:10.1103/PhysRevLett.89.027002

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Why an ac Magnetic Field Shifts the Irreversibility Line in Type-II Superconductors

Ernst Helmut Brandt, Grigorii P. Mikitik

DOI 10.1103/PhysRevLett.89.027002 · Physical Review Letters

T1

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Abstract

We show that for a thin superconducting strip placed in a transverse dc magnetic field—the typical geometry of experiments with high- Tc superconductors—the application of a weak ac magnetic field perpendicular to the dc field generates a dc voltage in the strip. This voltage leads to the decay of the critical currents circulating in the strip, and eventually the equilibrium state of the superconductor is established. This relaxation is not due to thermally activated flux creep but to the “walking” motion of vortices in the two-dimensional critical state of the strip with in-plane ac field. Our theory explains the shaking effect that was used for detecting phase transitions of the vortex lattice in superconductors.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YBa2Cu3O7-2δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Bi2Sr2CaCu2O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown