## Abstract

The deformations of a two-dimensional vortex lattice pinned by a random configuration of pinning centres are studied by a molecular dynamics annealing method. The pinning centres collectively induce a softening of the vortex lattice. The shear modulus decreases with increasing strength of the random potential. At a certain strength A_{plas}, the pinning centres start to induce plastic deformations in the vortex lattice. The lattice is distorted elastically only when the strength of the random potential is below A_{plas}. The vortex lattice is rapidly destroyed as the strength of the pinning centres is increased above A_{plas}. The cross-over value A_{plas} depends on the density of the pinning centres and decreases logarithmically with increasing system size. The dynamic response to an external applied force F_{dr} is investigated using diffusive dynamics. The time averaged centre of mass velocity, < v > versus F_{dr} (corresponding to the current-voltage characteristics of a type II superconductor) is measured. The response exhibits a strong cross-over at A_{plas}. There is no significant non-linearity in the < v > - F_{dr} curves for pinning strengths weaker than A_{plas}. At A_{plas}, a non-linear region appears whose size grows rapidly with increasing pinning strength. In the linear sections of the < v > - F_{dr} curves the vortex system moves coherently as a lattice. The non-linearity is caused by a fluid-like flow of the vortices.

Original language | English |
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Pages (from-to) | 367-372 |

Number of pages | 6 |

Journal | Cryogenics |

Volume | 29 |

Issue number | 3 SUPPL. |

DOIs | |

Publication status | Published - Mar 1989 |

Externally published | Yes |

## Keywords

- computer models
- flux pinning
- superconductors