Direct Imaging of Submicron Scale Defect-induced Birefringence in SrTiO$_{3}$ Bicrystals

TL;DR

This study employs near-field scanning optical microscopy to visualize submicron defect-induced birefringence in SrTiO$_{3}$ bicrystals, revealing spiral strain patterns that influence superconductor junction properties.

Contribution

It provides the first direct imaging of defect-induced strain fields in SrTiO$_{3}$ bicrystals using quantitative polarimetry.

Findings

Detected spiral-shaped strain patterns near defects

Linked defect strain patterns to synthesis process

Explained non-uniformity in superconductor junctions

Abstract

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 SrTiO$_{3}$ 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 non-uniformity in the characteristics of high temperature superconductor grain boundary junctions fabricated on SrTiO$_{3}$ bicrystals.