de Haas–van Alphen Oscillations for the Field Along c -axis in UTe 2

We performed de Haas-van Alphen (dHvA) experiments in the spin-triplet superconductor UTe 2 for magnetic field along the c-axis above 15 T. Three fundamental dHvA frequencies, named α 1 , α 2 and β corresponding to the cross sections of cylindrical Fermi surfaces (FSs) with large cyclotron effective masses (33-43 m 0) were detected. No other fundamental dHvA frequencies were detected at high frequency range, suggesting a cylindrical-shaped electron FS without connecting at the Z point of the Brillouin zone. However, the existence of small pocket FSs associated with extremely heavy masses cannot be fully excluded.