Effect of splayed pins on vortex creep and critical currents

We study the effects of splayed columnar pins on the vortex motion using re alistic London-Langevin simulations. At low currents vortex creep is strong ly suppressed, whereas the critical current j(c) is enhanced only moderatel y. Splaying the pins generates an increasing energy barrier against vortex hopping, and leads to the forced entanglement of vortices, both of which su ppress creep efficiently. On the other hand splaying enhances kink nucleati on and introduces intersecting pins, which cut off the energy barriers. Thu s the j(c) enhancement is strongly parameter sensitive. We also characteriz e the angle dependence of j(c) and the effect of different splaying geometr ies.