Regular Article

Effect of dc field on ac-loss peak in a commercial Bi:2223/Ag tape

¹ Karadeniz Technical University, Faculty of Science and Arts, Department of Physics, 61080 Trabzon, Turkey
² Gümüşhane University, Faculty of Engineering and Natural Sciences, Department of Physics Engineering, 29100 Gümüşhane, Turkey

^* e-mail: ibrahimduzgun@gumushane.edu.tr

Received: 27 July 2017
Received in final form: 16 October 2017
Accepted: 7 November 2017
Published online: 1 December 2017

Abstract

Measurements of the ac susceptibility in a commercial Bi:2223/Ag tape for some different ac magnetic field amplitudes, H_ac, in the presence of bias magnetic field H_dc directed along H_ac are reported. It is found that the peak values of the imaginary component of ac susceptibility χ″_max versus H_ac trace a valley for the orientation where applied field H_a perpendicular to wide face of the tape total. We note that the observation of the valley depends on various parameters such as field dependence parameter n in the critical current density, in the simple power law expression j_c = α(T)/Bⁿ, choice of the bias field H_dc together with selected ac field amplitudes H_ac, and dimension and geometry of sample studied. Our calculations based on critical state model with j_c = α(1 − T/T_cm)^p/Bⁿ using the fitting parameters of n = 0.25, p = 2.2, T_cm = 108 K gives quite good results to compare the experimental and calculated curves.