Critical temperature, critical current, and vortex loops in 3D anisotropicJosephson junction arrays

Monte Carlo simulations of a 3D anisotropic Josephson junction array are pe rformed, to determine the critical temperature T-c(I, alpha) for the onset of phase incoherence. Here I is the external current drive at opposite surf aces, and alpha = E-J perpendicular to/E-J parallel to is the inter-/intra- layer Josephson coupling ratio. T-c(I, alpha) is equivalent to a critical c urrent, I-c(T, alpha) fur the breakdown of global phase coherence. The temp erature and anisotropy dependence of I-c(T, alpha) supports a physical pict ure of two vortex populations, quasi-2D and 3D in nature at small and large scales respectively, separated by a length scale r(perpendicular to) simil ar to 1/root alpha.