Josephson modulation of the critical current inYBa2Cu3O7−δfilms

Abstract

Assuming that the boundary planes in YBa 2 Cu 3 O 7−␦ can show a Josephson behavior, we establish the conditions required in epitaxial thin films to observe the modulation of the critical current by an applied magnetic field, as well as the possible forms of the modulated current. We report measurements carried out on two YBa 2 Cu 3 O 7−␦ films in the near vicinity of the critical temperature that show a partial modulation of their critical current. The comparison of the measured critical current changes to those predicted by the calculations shows that the experimental results are consistent with the Josephson modulation of the current carried by associations of weak links located in the boundary planes.

Temperature-dependent critical currents in superconductingYBa2Cu3O7−δand ferromagneticDjupmyr1, Soltan2, Habermeier3 et al. 2009Phys. Rev. B

“…3. Bernstein et al 40 suggested that planar defects split up in structures that locally behave like Josephson weak links or superconducting-quantum-interference-device ͑SQUID͒-like structures. Since along the whole length of the APB there are all kind of defect structures expected, it is difficult to make an exact description.…”

Determination of the critical temperature and oxygen content variations along the c-axis of YBCO epitaxial films

“…The tunneling currents cannot flow across the boundary planes at the locations where, due to defects, the separation between both sides is large with respect to the coherence length. We have suggested that this results in the splitting of the boundary planes into rows of Josephson weak links [11,12] and established that ) T ( J S cr , for a YBCO film whose boundary planes include Z rows of Josephson weak links with the same T c , takes the form…”