MODELING OF THE HYSTERESIS LOOP FOR YBA2CU3O7-DELTA THIN-FILMS

A quantitative analysis of the response for YBa2Cu3O7-delta thin films in an external DC magnetic field (hysteresis loop) is presented, based on the critical-state model as proposed by Sun et al. [Phys. Rev. B 44 (1991) 5275]. This model is extended in order to take into account the dependence of the critical current J(c) on the applied field H(a) through a Kim-like expression J(c)(H(a)) = J(c)(0)/(1 +\H(a)\/B0). Analytical relations for the hysteresis cycle for this case are given. Moreover using this analysis and varying J(c)(0) and B0 as independent parameters, the experimental hysteresis loops can be fitted, for different temperatures (T = 5-80 K). The temperature dependence of B0 and J(c) are presented and discussed as well.