Edge critical currents of dense Josephson vortex lattice in layered superconductors

Abstract

We calculate the field dependence of the critical current for the dense Josephson vortex lattice which is created by large magnetic field B applied along the layers of atomically layered superconductors. In clean samples a finite critical current appears due to the interaction of the lattice with the boundaries. The boundary induces an alternating deformation of the lattice decaying inside the sample at the typical length, which is larger than the Josephson length and increases proportional to the magnetic field. The exact shape of this deformation and the total current flowing along the surface are uniquely determined by the position of the lattice in the bulk. The total maximum Josephson current has overall 1/B dependence with strong oscillations. In contrast to the wellknown Fraunhofer dependence, the period of oscillations corresponds to adding one flux quantum per two junctions. Due to interaction with the boundaries, the flux-flow voltage for slow lattice motion also oscillates with field, in agreement with recent experiments.

Origin of flux-flow resistance oscillations inBi2Sr2CaCu2O8+y

“…These exciting experiments were interpreted both analytically 5 and numerically 6,7 by several authors. One of the important questions to be answered was whether the flux lattice correspond to a triangular lattice ͑antiphase ordering with possible cancellation of the sum voltage at the junction end͒ or a square lattice ͑in-phase ordering leading to a large sum voltage at the junction end͒.…”

Josephson Vortices in High Tc Superconductors

“…The boundary magnetic field B TR between triangular and rectangular lattice is defined as B TR =w 0 /2 2 s 3 (Koshelev 2002), which is also well coincided with experiments & Hirata K. 2003. On contrary, it is useful to determine the anisotropic parameter from the JV flow resistance measurement directly.…”

“…When the surface potential is smaller than the energy of JV-system flowing with Lorentz force by the larger applied current, it is expected that the periodic oscillations would be smeared out. This is the speculation from the experimental results, but it was confirmed theoretically by analytical method (Koshelev 2002;Ikeda 2002) and numerical calculations (Machida 2003).…”

“…Recently we have found a new method to study the magnetic phases of JV system by using the periodic oscillations in flow resistance of JVs (Ooi et al 2002), from which we can deduce the configurations of JVs. This phenomenon is caused by the intrinsic boundary effect of the sample, related to the configurations of JVs (Ooi et al 2002;Koshelev 2002;Machida 2003). The magnetic phase, in which the periodic oscillations are observed, has been confirmed as a three-dimensional (3D) ordered vortex state.…”

Shapiro Steps in BSCCO Intrinsic Josephson Junctions

“…Actually, there are many excellent works for the effect of magnetic field on the BSCCO IJJs. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] It is sure that a pioneering work done by Sakai, Bodin and Pedersen(SBP) [20] is the starting point to understand the fluxon dynamics in BSCCO IJJs with a stacking structure.We adopt here a unified theory proposed by Machida and Sakai (MS) [29], which includes both the electric and magnetic field couplings between neighboring IJJs in multistacked structure. The MS-unified theory is a further extension of the model proposed by Sakai, Bodin and Pedersen (SBP).…”