Dynamical phase diagrams for moving vortices interacting with periodic pinning

Article

关键词: JOSEPHSON-JUNCTION ARRAYS;    FLUX-LINE-LATTICE;    DRIVEN VORTEX LATTICES;    PLASTIC-FLOW;    SUPERCONDUCTORS;    SYSTEMS;    2H-NBSE2;    DEFECTS;    SITES;   

DOI  :  10.1103/PhysRevB.66.054523

来源: SCIE

【 摘 要 】

The dynamical phase diagrams for vortices in clean films, driven by a uniform force and interacting with periodic pinning resulting from a columnar-defect lattice, are investigated by numerical simulations of a London model and other considerations. Dynamical phases are identified according to the spatial symmetry, and dynamical phase diagrams are studied as a function of the driving force magnitude and direction, and on the temperature, for typical vortex densities. The theoretical limit of infinite drive-force magnitudes is investigated first. In this limit vortex motion averages the periodic pinning potential in the direction of motion, and the dynamical phases reduce to thermal equilibrium ones for vortices interacting with the averaged pinning potential. For most directions of motion this potential is essentially constant. For a few particular ones it is a one-dimensional washboard, periodic in the direction transverse to motion. The dynamical phase diagrams in this limit are obtained as a function of the direction of motion and temperature by equilibrium Monte Carlo simulations. They contain moving vortex lattices, commensurate or incommensurate with the washboards periodicities, at low temperatures, moving smectics, and moving liquids at higher ones. Finite-drive dynamical phase diagrams are then obtained by numerical solution of Langevin equations. It is found that each dynamical phase originates from an infinite-drive limit phase with the same spatial symmetry that evolves continuously into finite-drive regions of the dynamical phase diagram. Dynamical transitions between moving commensurate or incommensurate lattices and moving liquids and between moving commensurate lattices and moving smectics are observed. Transverse pinning of vortices at low temperatures is found in regions of the dynamical phase diagrams where the dynamical phases are moving commensurate lattices or moving smectics.

【 授权许可】

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