*

We report evidence of significant surface normal fluid response from a chiral spin-triplet pairing state of UTe₂. The microwave surface impedance of UTe₂ crystals was measured and converted to complex conductivity. The anomalous residual real part of conductivity in the zero temperature limit supports the presence of a significant normal fluid response in the ground state. The imaginary part of conductivity follows the low temperature behavior predicted for the axial spin-triplet state, which is further narrowed down to the chiral spin-triplet state with evidence of broken time-reversal symmetry [1]. The imaginary part of conductivity also reveals a low impurity scattering rate and low frequency-to-energy-gap ratio, implying that the observed normal fluid response is not due to an extrinsic origin. Candidate mechanisms such as a surface Majorana normal fluid, which is predicted for the chiral spin-triplet superconductor, will be discussed.

[Ref] S. Bae, et al., arXiv:1909.09032 (2019)
[1] I. M. Hayes, et al., arXiv:2002.02539 (2020).