Flux trapping in a macroscopic cylinderical hole drilled in
Bi-Sr-Ca-Cu-O |
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Authors: | A Kiliç K Kiliç H Yeti? M Oluta? A Altinkok H Sözeri O Çetin |
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Institution: | (1) Department of Physics, Turgut Gulez Research Laboratory, Abant Izzet Baysal University, 14280 Bolu, Turkey;(2) National Metrology Institute TUBITAK P.O. Box 21, 41470, Gebze-Kocaeli, Turkey |
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Abstract: | The flux dynamics in a polycrystalline sample of
Bi1.7Pb0.3Sr2Ca2Cu3Ox with a macroscopic
cylindrical hole (CH) drilled was investigated by slow transport relaxation
(V-t curves) and magnetovoltage measurements (V-H curves). It was monitored that
there are several discontinuities in the time evolution of quenched state in
V-t curves, which was attributed to the leaving of quantized flux lines
trapped through CH together with surface superconducting effects. We
observed that asymmetric V-H curves demonstrate unusual remarkable counter
clockwise hysteresis effects upon cycling of field. This interesting result
was correlated mainly to the flux trapping inside the CH that acts as a
macroscopic attractive pinning center for flux lines. Further, the
hysteresis effects in V-H curves for a fixed transport current provide a direct
evidence that the number of flux lines, measured dissipation and relative
decrease/increase in irreversibilities could be determined by sweeping rate
of external magnetic field (dH/dt) which leads also to peculiar time effects. |
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Keywords: | 74 72 Hs Bi-based cuprates 74 25 Qt Vortex lattices flux pinning flux creep |
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