Rotating vortex-lattice rings in superconductors

We report on dynamics of superconducting vortices driven by a radial current in a Corbino disk, where the vortices rotate around the center of the sample by feeling a frustrated Lorentz force inversely proportional to the radius. Based on a mode-locking resonance, we have revealed the formation of rotating vortex rings composed of triangular-lattice arrays. Both at high (4.1 K) and low (2.1 K) temperatures, we have observed the change in the lattice orientation with respect to the flow direction under decreasing field.