Experimental evidence for a large critical transverse depinning force in weakly-pinned vortices

We present experimental evidence for the existence of a large critical transverse depinning force. These results are obtained in the weakly-pinned superconducting metal glasses Fe$_{x}$Ni$_{1-x}$Zr$_{2}$ using crossed ac and dc driving currents. We study the depinning force due to the transverse ac drive as a function of a longitudinal dc drive. The ac/dc combination allows us to separate the transverse drive from the longitudinal one. We show that the force required for depinning in the transverse direction is enhanced by a longitudinal drive, which leads to the existence of a large transverse critical force.