Y-Ba-Cu-O grain boundary resistivity above and below the critical temperature

The interface resistance of YBa₂Cu₃O_7-δ grain boundaries has been measured in the range 5-270 K by means of a Wheatstone bridge for 24°, 30° and 36° symmetric and 45° degree asymmetric, [001] tilt, thin film grain boundaries. A number of preliminary experiments have demonstrated the validity of the technique employed. Above T_c, the grain boundary resistance decreases as the temperature is increased, and the temperature variation is more pronounced for higher angle boundaries. A number of possibilities for interpreting the data are considered.