Evidence of Fermi surface reconstruction at the metamagnetic transition of the strongly correlated superconductor UTe2

Thermoelectric power (S) and Hall effect (RH) measurements on the paramagnetic superconductor UTe2 with the magnetic field applied along the hard magnetization b axis are reported. The first-order nature of the metamagnetic transition at Hm=Hc2b=35 T leads to drastic consequences on S and RH. In contrast to the field dependence of the specific heat in the normal state through Hm, S(H) is not symmetric with respect to Hm. This implies a strong interplay between ferromagnetic fluctuations and a Fermi-surface reconstruction at Hm. RH is very well described by incoherent skew scattering above the coherence temperature Tm corresponding roughly to the temperature of the maximum in the susceptibility Tχmax and coherent skew scattering at lower temperatures. The discontinuous field dependence of both S(H) and the ordinary Hall coefficient R0, at Hm and at low temperature, provides evidence of a change in the band structure at the Fermi level.