Critical behaviors of triangular Josephson junction arrays in a magnetic field

The critical properties of a vortex-solid-melting transition in triangular Josephson junction arrays (JJA's) exposed to a magnetic field are studied with a focus on the fillings f = 1/2, 2/5, and 1/36 by analyzing the superconducting scaling behavior of the I-V characteristics. It is found that the vortex-solid-melting transition at f = 2/5 and 1/36 exhibits an unusually large correlation-length critical exponent (v > 1) and a small dynamical critical exponent (z <= 1). For f = 1/2, the transition is found KT (Kosterlitz-Thouless)-like in contrast to previous experimental observations. We discuss implications of the experimental results in conjunction with domain-wall excitations. (c) 2005 Elsevier Ltd. All rights reserved.