Eur. Phys. J. B 50, 565–569 (2006) DOI: 10.1140/epjb/e2006-00180-3 T HE EUROPEAN P HYSICAL JOURNAL B Flux trapping in a macroscopic cylinderical hole drilled in Bi-Sr-Ca-Cu-O A. Kili¸ c 1, a , K. Kili¸ c 1 , H. Yeti¸ s 1 , M. Oluta¸ s 1 , A. Altinkok 1 , H. S¨ ozeri 2 , and O. C ¸ etin 1 1 Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu, Turkey 2 National Metrology Institute TUBITAK P.O. Box 21, 41470, Gebze-Kocaeli, Turkey Received 7 December 2005 / Received in final form 4 March 2006 Published online 17 May 2006 – c  EDP Sciences, Societ`a Italiana di Fisica, Springer-Verlag 2006 Abstract. The flux dynamics in a polycrystalline sample of Bi1.7 Pb0.3Sr2Ca2Cu3Ox with a macroscopic cylindrical hole (CH) drilled was investigated by slow transport relaxation (V - t curves) and magneto- voltage 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 inter- esting 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. PACS. 74.72.Hs Bi-based cuprates – 74.25.Qt Vortex lattices, flux pinning, flux creep 1 Introduction In type-II superconductors, the flux dynamics is governed by two competing physical mechanisms, attractive inter- action between flux lines and pinning centers which are randomly distributed inside the sample, and repulsive in- teraction of flux lines which favors order [1,2]. In order to increase their pinning properties, artificial columnar de- fects can be produced by heavy-ion irradiation [3, 4], which can cause considerably an enhancement in the pinning ef- ficiency and current carrying capacity of the material. In addition, the advances in lithographic techniques allow to fabricate antidotes which act as strong pinning centers under suitable conditions [5–7]. For instance, it is possi- ble to fabricate well ordered arrays of columnar defects in superconducting thin films with radius comparable to co- herence length ξ by using high resolution of electron beam lithography technique [6]. Matching between the regular array of columnar defects and the flux line lattice can be obtained by adjusting the external magnetic field being in the form of integer multiple or some fraction of matching fields, i.e., commensurability effects [6]. The aim of this study is to investigate the time dependent flux motion in a polycrystalline sample of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O x (BSCCO) drilled cylindrical hole (CH) with a diameter of 0.5 mm. We present the results of slow transport relaxation (V - t curves) and magnetovolt- age (V - H curves) measurements with different sweeping a e-mail: kilic a@ibu.edu.tr rate (dH /dt) of external magnetic field in a polycrystalline sample of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O x (BSCCO) drilled cylin- drical hole (CH) with a diameter of 0.5 mm. Several dis- continuities observed in the time evolution of quenched state of the V - t curves are interpreted in terms of leav- ing of quantized flux lines through CH. We show that dH /dt becomes an important parameter in the evolution of V - H curves, which determines the measured dissipa- tion and degree of relative irreversible effects. For different values of dH /dt, pronounced counter clockwise hysteresis effects appearing in asymmetric V -H curves is considered as a direct evidence of flux trapping in CH that sets an attractive potential energy for flux lines. The results are compared to those of similar measurements performed on the same BSCCO sample before drilling of CH. Finally we suggest that investigation of such a macroscopic CH via V - t and V - H curves will provide a direct contribution to designing of superconducting quantum interference de- vices (SQUIDs). In these devices, a few strategically intro- duced holes can trap the vortices and reduce profoundly the noise by increasing their performance. 2 Experiment Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O x sample has been prepared from the high purity powder of B 2 O 3 , PbO, SrCO 3 , CaCO 3 and CuO by using the conventional solid state reaction method. The dc electrical resistivity measurements were carried out using standard four point method on BSCCO