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Abstract: We study the vortex ratchet effects in superconducting
asymmetric curved bridges. By transport measurements, we find that the
rectified dc voltages are significantly enhanced, and we obtain clearly
asymmetric voltage waveforms versus time in one period. The
rectification effect can be achieved in a very wide range of
temperatures, currents and magnetic fields. Based on the simulations of
time-dependent Ginzburg-Landau equations, we demonstrate that the giant
ratchet effects are mainly caused by the collective behavior of vortices
in this asymmetric structure, which is quite different to the matching
effects in conventional vortex ratchet systems.