Raman study of the 90 degrees grain boundaries in YBa2Cu3O7-delta thin films

Abstract

YBa2Cu3O7-delta (YBCO) films containing two different types of 90 degrees grain boundaries were fabricated on the same substrates. Raman spectra from several parts of the basal-plane-faced tilt (TL) grain boundaries were measured and compared with those from the twist (TW) grain boundaries. The Raman results show that I(500)/I(340), the relative intensity of the A(1g) mode near 500 cm(-1) with respect to that of the B-1g mode near 340 cm(-1), is suppressed in the TL boundaries, relative to the TW boundaries. The results can be interpreted to mean that the stress is stronger in the TL boundaries than in the TW boundaries. This may offer an alternative explanation for the weak-link behavior of the step-edge Josephson junctions. (C) 1999 Published by Elsevier Science B.V. All rights reserved.