Dynamical phase transition in a fully frustrated Josephson array on a square lattice

Abstract

We study dynamical phase transitions at temperature T = 0 in a fully frustrated square Josephson junction array subject to a driving current density which has nonzero components ix, iy parallel to both axes of the lattice. Our numerical results show clear evidence for three dynamical phases: a pinned vortex lattice characterized by zero time-averaged voltages vx t and vy t, a "plastic" phase in which both vx t and vy t are nonzero, and a moving lattice phase in which only one of the timeaverage voltage components is nonzero. The last of these has a finite transverse critical current: if a current is applied in the x direction, a nonzero transverse current density iy is required before vy t becomes nonzero. The voltage traces in the moving lattice phase are periodic in time. By contrast, the voltages in the plastic phase have continuous power spectra which are weakly dependent on frequency. This phase diagram is found numerically to be qualitatively unchanged by the presence of weak disorder. We also describe two simple analytical models which recover some, but not all, the characteristics of the three dynamical phases, and of the phase diagram calculated numerically. 74.60.Ge,74.50.+r,74.60.Jg

Critical currents and vortex states at fractional matching fields in superconductors with periodic pinning

“…32 Simulations of Josephson-junction arrays have also found plastic and elastic vortex flow phases and transverse depinning transitions. 33,34 The dynamics of vortices in periodic pinning arrays with B/B Ͻ1 has not previously been studied. For this case, some of the open questions are ͑i͒ whether the vortex configurations in the pinned state are the same as the moving vortex configuration; ͑ii͒ how this depends on the filling fraction; and ͑iii͒ whether there can be plastic flow and how it depends on commensurability.…”

Phase transition in current-biased arrays of small Josephson junctions

“…[35][36][37][38][39][40][41][42][43][44] When the array has even weak disorder, as well as a finite current and a finite applied magnetic field, these arrays have a rich variety of behavior, with transitions between pinned and different kinds of moving ordered or partially ordered vortex states. 10 For example, Fisher et al 41 have investigated phase transitions at a field of one-half flux quantum per plaquette. In this case, the phase diagram represents regions of phase space in which a vortex lattice is either unpinned or pinned by a periodic pinning potential.…”

Moving vortex phases, dynamical symmetry breaking, and jamming for vortices in honeycomb pinning arrays

“…[15][16][17][18]20,25,30,31,33 Since a number of distinct ordered and partially ordered vortex states can be created in periodic pinning arrays, a much richer variety of dynamical vortex behaviors occur for periodic pinning than for random pinning arrays. [16][17][18][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] Several of the dynamical phases occur due to the existence of highly mobile interstitial vortices which channel between the pinned vortices. 16,18,[36][37][38]40,41,43,44,46,50 As a function of applied drive, various types of moving phases occur, including interstitial vortices moving coherently between the pinning sites in one-dimensional paths 16,18,[34][35][36][37]40,…”

“…16,18,[36][37][38]40,41,43,44,46,50 As a function of applied drive, various types of moving phases occur, including interstitial vortices moving coherently between the pinning sites in one-dimensional paths 16,18,[34][35][36][37]40,44 or periodically modulated winding paths, 34,36,45,46 disordered regimes where the vortex motion is liquidlike, 34,36,40,44 and regimes where vortices flow along the pinning rows. 34,39,[47][48][49] Other dynamical effects, such as rectification of mixtures of pinned and interstitial vortices, can be realized when the periodic pinning arrays are asymmetric. 50 Most of the studies of vortex ordering and dynamics in periodic pinning arrays have been performed for square and triangular arrays.…”