Discovery of new vortex state in TaSe3 topological ring crystals

We have measured the magnetic torque of the ring-shaped crystals of TaSe3 by using piezoresistive cantilevers in order to investigate the superconducting topological properties. We measured three ring samples and we observed that the magnetic torque of the ring crystals oscillates with increasing the external magnetic field. The first peak of Sample A (radius: 37.9μm) was 1.21 Gauss and that of Sample B (24.5μm) was 3.70 Gauss and that of Sample C (15.6μm) was 4.73 Gauss, respectively. We found that the first peak depends on the length of the circumference itself. If there are such relation between the peak field and the length of the circumference, it is natural that vortices in the ring crystal were placed along the circumference. From these results, we suggest that vortices exist as cylinder vortices in the rings and this phenomenon gives a new experimental evidence of topological effect in superconductor.