Tuesday, 08/19/08

Session Title:	Flux Pinning and Dynamics II - Engineered Pinning Arrangements
Session Chairs:	Paul Barnes, Air Force Research Laboratory, Wright-Patterson AFB & Takanobu Kiss, Kyushu University
Paper Number:	2MPD05
Start Time:	10:00am
Session Type:	Poster

Mixed-state Hall effect in YBCO Thin Films with an Artificial Pinning Lattice L.-M. Wang, C.-C. Guo, W.-J. Hwang, J.-Y. Jong, J.-H. Chen, Department of Electrical Engineering, Da-Yeh University

The mixed-state longitudinal (roh_xx) and transverse (roh_xy) resistivities were examined in order to study the effect of flux pinning in an YBa2Cu3Oy (YBCO) thin films with an artificial anti-dot lattice. The antidotes were arranged in a rectangular array with lattices parameters of a = 1 μm and b = 1.5 μm, and extend over 100 μm x 100 μm areas by e-beam lithography process. The activation energy U, roh_xx, Hall coefficient R_H, and roh_xy were measured with currents applied along the a-axis and b-axis directions of the rectangular array, respectively. It was observed that the sign reversal of the Hall coefficient R_H diminishes within the measured configuration with current applied along the a axis of the rectangular array, accompanying an observed decrease of U. This implies that the mechanism of flux flow may be the most important origin of the anomalous Hall effect and the sign reversal of R_H is sensitive to the flux pinning. In addition, the exponent beta in scaling behavior roh_xy ~ (roh_xx)^beta is magnetic field dependent and becomes smaller when the current is applied along the a axis of the rectangular array. The experimental results are discussed within the framework of vortex-dynamics theories.