Superconductivity and flux pinning in Y and heavily Pb codoped Bi-2212 single crystals
This article was originally published as: Wang, XL, Liu, HK, Dou, SX, Horvat, J, Millikon, D, Heine, G, Lang, W, Luo, HM & Ding, SY, Superconductivity and flux pinning in Y and heavily Pb codoped Bi-2212 single crystals, Journal of Applied Physics, 2001, 89(11), 7669-7671, and may be found here. Copyright 2001 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
Studies of superconductivity and flux pinning were carried out on (Bi1.64Pb0.36)Sr2Ca1–xYxCu2O8 + y (x = 0, 0.05, 0.11, 0.33) single crystals grown by the self-flux method. X-ray diffraction, transport, and magnetic measurements were performed for purposes of characterization. X-ray analysis revealed that the c lattice parameter systemically decreases as the Y doping level increases. The superconducting transition temperature Tc decreases from 80 to 30 K as x increases. A strong annealing effect on Tc and superconducting volume has been observed. Resistance measurements show that x = 0.33 samples are semiconductive over a wide temperature range between 4.2 and 300 K for the as-grown state, but become metallic with Tc of 65–70 K after air or oxygen annealing. Flux pinning was studied by measuring the hysteresis loop at different temperatures and different fields. A peak effect was observed in all the codoped samples. Results show that at low temperatures, the peak field is smaller than in solely Pb doped crystals and decreases as x increases (x>0.1). However, the peak field at high temperature for the x = 0.05 sample is higher than in heavily Pb doped Bi2212 crystals, indicative of a strong pinning due to the codoping.
X. L. Wang, H. K. Liu, S. X. Dou, J. Horvat, D. Millikon, G. Heine, W. Lang, H. M. Luo, and S. Y. Ding. "Superconductivity and flux pinning in Y and heavily Pb codoped Bi-2212 single crystals" Faculty of Engineering - Papers (2001).
Available at: http://works.bepress.com/xlwang/37