Direct Imaging of Submicron Scale Defect-induced Birefringence in SrTiO3 Bicrystals

Using a near-field scanning optical microscope capable of quantitative polarimetry, we map the anisotropic strain fields associated with individual submicron defects near the fusion boundaries of SrTiO3 bicrystals. Many defects exhibit unexpected spiral-shape strain patterns, whose handedness is believed to be linked to the bicrystal synthesis process. Direct observation of these defect-induced strain fields helps explain previously observed nonuniformity in the characteristics of high temperature superconductor grain boundary junctions fabricated on SrTiO3 bicrystals. PACS numbers: 61.72.Hh, 07.79.Fc, 78.20.Fm, 61.72.Mn Typeset using REVTEX