FeSe$_{0.5}$Te$_{0.5}$ thin film Josephson junction on SrTiO$_{3}$ bicrystal substrates

Josephson junctions were fabricated in the epitaxial FeSe$_{0.5}$Te$_{0.5}$ thin films on [100] tilted SrTiO$_{3}$ bicrystal substrates with a CeO$_{2}$ buffer layer. These junctions with a 24 degree of grain boundary misorientation show a typical resistive-shunt-junction like current-voltage behavior. Critical current densities across the grain boundary in these junctions were observed to be remarkably suppressed and modulated by the magnetic field. Films without the grain boundary show a critical current density much higher than those with the grain boundary. These results indicate a Josephson Effect in those grain boundary junctions.