Local observation of linear-$T$ superfluid density and anomalous vortex dynamics in URu${}_2$Si${}_2$

Abstract

The heavy fermion superconductor URu${}_2$Si${}_2$ is a candidate for chiral, time-reversal symmetry-breaking superconductivity with a nodal gap structure. Here, we microscopically visualized superconductivity and spatially inhomogeneous ferromagnetism in URu${}_2$Si${}_2$. We observed linear-$T$ superfluid density, consistent with d-wave pairing symmetries including chiral d-wave, but did not observe the spontaneous magnetization expected for chiral d-wave. Local vortex pinning potentials had either four- or two-fold rotational symmetries with various orientations at different locations. Taken together, these data support a nodal gap structure in URu${}_2$Si${}_2$ and suggest that chirality either is not present or does not lead to detectable spontaneous magnetization.