Evidence of Fermi surface reconstruction at the metamagnetic transition of the strongly correlated superconductor UTe_{2}

Thermoelectric power (S) and Hall effect (R_{H}) measurements on the paramagnetic superconductor UTe_{2} with the magnetic field applied along the hard magnetization b axis are reported. The first-order nature of the metamagnetic transition at H_{m}=H_{c2}^{b}=35 T leads to drastic consequences on S and R_{H}. In contrast to the field dependence of the specific heat in the normal state through H_{m}, S(H) is not symmetric with respect to H_{m}. This implies a strong interplay between ferromagnetic fluctuations and a Fermi-surface reconstruction at H_{m}. R_{H} is very well described by incoherent skew scattering above the coherence temperature T_{m} corresponding roughly to the temperature of the maximum in the susceptibility T_{χ_{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_{m} and at low temperature, provides evidence of a change in the band structure at the Fermi level.