Superconductivity and electric field effect of 90 degree grain boundaries in YBa2Cu3O7-x thin films

Abstract

three terminal devise was fabricated by depositing YBa2Cu3O7-x (YBCO) thin films containing 90 degree grain boundaries which was covered with a SrTiO3 gate layer and an Au gate electrode. YBCO thin films were grown by bi-epitaxial process on LaSrGaO4(100) substrate. The resistance versus temperature curve of the YBCO microbridge containing 90 degree grain boundaries showed double resistive transitions. This result was interpreted by the weak link effect of 90 degree grain boundaries in YBCO thin films. A large electric field effect on 90 degree grain boundaries was observed. The superconducting transition temperature of the 90 degree grain boundaries was modulated up to 11.4% by applying an electric field of 4 x 10(4) V/cm.