Local observation of linear-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>T</mml:mi></mml:math> superfluid density and anomalous vortex dynamics in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">U</mml:mi><mml:msub><mml:mi>Ru</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Si</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Yusuke Iguchi, Irene P. Zhang, E. D. Bauer, F. Ronning, J. R. Kirtley, Kathryn A. Moler
Abstract
The heavy fermion superconductor $\mathrm{U}{\mathrm{Ru}}_{2}{\mathrm{Si}}_{2}$ 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 $\mathrm{U}{\mathrm{Ru}}_{2}{\mathrm{Si}}_{2}$. 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 twofold rotational symmetries with various orientations at different locations. Taken together, these data support a nodal gap structure in $\mathrm{U}{\mathrm{Ru}}_{2}{\mathrm{Si}}_{2}$ and suggest that chirality either is not present or does not lead to detectable spontaneous magnetization.