Bv. Kumaraswamy et al., LOW-FIELD AC-SUSCEPTIBILITY STUDY OF FLUX-CREEP IN METAL-SUBSTITUTED ERBA2CU3O7-DELTA, Physical review. B, Condensed matter, 52(2), 1995, pp. 1320-1324
Low-field ac-susceptibility studies of pure ErBa2Cu3O7-delta and subst
ituted samples of ErBa2(Cu(0.995)M(0.005))(3)O-7-delta (M=Fe, Co, Ni,
Ga) have been carried out in the frequency range up to 1 kHz. The acti
vation energy for flux creep in the case of the doped samples is consi
derably lower than that for the undoped sample. The analysis of the re
sults within the framework of Muller's model [Physica C 159, 717 (1989
); 168, 585 (1990)] shows that the intergrain critical current density
gets considerably suppressed by the dopants. Employing a SIS junction
model it is argued that this can be attributed to the reduction in th
e Fermi energy of the system due to the localization caused by the pre
sence of the dopant atoms.