Weak links and critical current density in Bi2Sr2CaCu2Ox thin films

Abstract

Magnetization measurements were performed on epitaxial and textured Bi2Sr2CaCu2Ox thin films deposited on (100) LaAlO3 and MgO substrates. An anomalous dependence of the critical current density derived from magnetization hysteresis measurement on magnetic field is observed. The measured critical current density shows a minimum at a magnetic field (Hm) far below the upper critical field Hc2. The measured Hm in epitaxial films has an exponential dependence on temperature, e−T/T0 (T0∼12.5 K). The anomalous field dependence of critical current density is attributed to the presence of weak links in the films.