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, base d 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). Ana lytical relations for the hysteresis cycle for this case are given. Mo reover using this analysis and varying J(c)(0) and B0 as independent p arameters, the experimental hysteresis loops can be fitted, for differ ent temperatures (T = 5-80 K). The temperature dependence of B0 and J( c) are presented and discussed as well.