Flux pinning and critical currents by Mo-substitution in YBa2Cu3O7−δ

Abstract

Mo-substituted samples with stoichiometric composition YBa 2 (Cu 1− x Mo x ) 3 O 7−δ , where 0 < x < 0.04, prepared under identical conditions have been characterized by d.c. magnetization and thermogravimetric analysis measurements. D.C. magnetization measurements on randomly oriented powdered systems, as a function of temperature and field, exhibit an M ( H ) hysteresis loop, indicative of moderate flux pinning even as T approaches T c . We feel that this flux pinning arises due to the preferential substitution of Mo on the Cu-site, which acts as a pinning centre. Intragrain critical current density, J c , values deduced from magnetization measurements for x = 0.01−0.04 at H = 5 kOe and T = 15 K decrease with increasing Mo concentration due to decreasing free carrier concentration, p .