Search

An inhomogeneous grain boundary critical current density was observed in high temperature grain boundary junctions combined with a d(sub x2-y2) symmetry component of the order parameter. The effect is more apparent in grain boundaries with asymmetric 45-degree tilt. A negative critical current density was also observed for a large fraction of the junctions' facets, leading to highly anomalous magnetic field dependences.

The magnetic properties of thin film pickup loop structures for a superconducting quantum interference device magnetometer are investigated at sub-micrometer dimensions. The structures, which were designed using a three-level-of-metal approach, are analyzed for their magnetic coupling behavior. Results show that the performance of the loop structures is strongly affected by the design of the low-inductance interconnect structure.

Reports on the demonstration of a miniature vector magnetometer for imaging three orthogonal components of the magnetic field in close proximity to a planar sample. What the magnetometer consists of; Information on the z-axis Superconducting Quantum Interference Device (SQUID).

Grain boundary junctions in high-T/sub c/ thin films generally consist of facets with typical dimensions below 100 nm. In combination with a d(x/sup 2/-y/sup 2/) symmetry component of the order parameter, this faceting gives rise to an inhomogeneous critical current density J/sub c/ along the grain boundary. The inhomogeneity is most prominent for asymmetric 45/spl deg/ [001] tilt grain boundaries. For a large fraction of the facets in these boundaries the order parameter orientation gives rise to an additional /spl pi/ phase difference, and therefore to a 'negative' critical current density. This leads to highly anomalous magnetic field dependences of the critical current. Direct imaging with scanning SQUID microscopy provides evidence that magnetic flux is generated spontaneously in these boundaries. These observations have several significant implications, both for understanding the properties of grain boundaries in high-T/sub c/ superconductors and for their applications. [ABSTRACT FROM PUBLISHER]