Vortex Structure and Dynamics in Kagome and Triangular Pinning Potentials

M.F. LAGUNA, C.A. BALSEIRO, D. DOMINGUEZ, FRANCO NORI

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

The American Physical Society

Lugar: U.S.A.; Año: 2001 vol. 64 p. 104505 - 104518

0163-1829

We study the dynamics of thermally driven superconducting vortices in two types of periodic pinning potentials: kagome and triangular. For the first, second, and third matching fields, we obtain the corresponding ground-state vortex configurations and their phase diagrams. We analyze the system properties by looking at the vortex trajectories and the structure factor, as well as the linear and angular diffusion. The temperature versus pinning force phase diagram is analyzed in detail for each matching field. When the temperature is varied, we observe several stages of lattice pinning and melting. In most of the cases we find, for decreasing temperature, first a pinning of vortices and afterwards a freezing transition of the interstitial vortices. The intermediate regime corresponds to interstitial vortices in a confined liquidlike state and pinned vortices. The kagome pinning potential shows interesting behavior at low temperatures: there is a phase with rotating vortextriangles caged by kagome hexagons ‘‘cooperative ring elementary excitations’’ , and there is geometric frustration for T → 0 with a nearly degenerate ground state.