Abstract
We study the dependence of the transport properties of square Josephson Junction arrays with the direction of the applied dc current, both experimentally and numerically. We present computational simulations of current–voltage curves at finite temperatures for a single vortex in an array of junctions and experimental measurements in arrays under a low magnetic field corresponding to We find that the transverse voltage vanishes only in the directions of maximum symmetry of the square lattice: the [10] and [01] direction (parallel bias) and the [11] direction (diagonal bias). For orientations different from the symmetry directions, we find a finite transverse voltage that depends strongly on the angle of the current. We find that vortex motion is pinned in the [10] direction meaning that the voltage response is insensitive to small changes in the orientation of the current near We call this phenomenon orientational pinning. This leads to a finite transverse critical current for a bias at and to a transverse voltage for a bias at On the other hand, for diagonal bias in the [11] direction the behavior is highly unstable against small variations of leading to a rapid change from zero transverse voltage to a large transverse voltage within a few degrees. This last behavior is in good agreement with our measurements in arrays with a quasidiagonal current drive.
- Received 14 January 2000
DOI:https://doi.org/10.1103/PhysRevB.62.4096
©2000 American Physical Society