Evidence of Fermi-Surface Reconstruction at the Metamagnetic Transition of the Strongly Correlated Superconductor UTe2

Thermoelectric power ($S$) and Hall effect ($R_mathrm{H}$) measurements on the paramagnetic superconductor UTe$_2$ with magnetic field applied along the hard magnetization $b$-axis are reported. The first order nature of the metamagnetic transition at $H_mathrm{m}=H^b_mathrm{c2}=35$~T leads to drastic consequences on $S$ and $R_mathrm{H}$. In contrast to the field dependence of the specific heat in the normal state through $H_mathrm{m}$, $S(H)$ is not symmetric with respect to $H_mathrm{m}$. This implies a strong interplay between ferromagnetic (FM) fluctuations and a Fermi-surface reconstruction at $H_mathrm{m}$. $R_mathrm{H}$ is very well described by incoherent skew scattering above the coherence temperature $T_mathrm{m}$ corresponding roughly to the temperature of the maximum in the susceptibility $T_{chi_mathrm{max}}$ and coherent skew scattering at lower temperatures. The discontinuous field dependence of both, $S(H)$ and the ordinary Hall coefficient $R_0$, at $H_mathrm{m}$ and at low temperature, provides evidence of a change in the band structure at the Fermi level.