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

Abstract

Monte Carlo simulations of a 3D anisotropic Josephson junction array are performed, to determine the critical temperature T c(I,α) for the onset of phase incoherence. Here I is the external current drive at opposite surfaces, and α ≡E_J⊥/E_J// is the inter-/intra-layer Josephson coupling ratio. T _c(I,α) is equivalent to a critical current, I _c(T,α) for the breakdown of global phase coherence. The temperature and anisotropy dependence of I _c(T,α) supports a physical picture of two vortex populations, quasi-2D and 3D in nature at small and large scales respectively, separated by a length scale r⊥~1/√α.