We have performed transport measurements in magnetic fields (H//c) up to 10T on a series of YBa2Cu3U7 grain boundaries induced by epitaxial growth on a substrate containing a series of step edges. For this material we find an activation energy which goes as U(T)~(l-t). Electric field versus current density curves taken at a constant temperature while varying the magnetic field allows a determination of the magnetic field dependence of the activation energy using the Ambagaokar-Halperin model. These values agree with results extracted from the resistive transitions. Similar characterizations of a sample of TlBa2Ca2Cu30x are also presented. The temperature dependence of the activation energy for this system may be summarized as U(T)~(l-t)2, suggesting that the grain boundaries behave as SNS juctions.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering