de Haas–van Alphen Oscillations for the Field Along c-axis in UTe₂

We performed de Haas–van Alphen (dHvA) experiments in the spin-triplet superconductor UTe₂ for magnetic field along the c-axis above 15T. Three fundamental dHvA frequencies, named α₁, α₂, and β corresponding to the cross sections of cylindrical Fermi surfaces (FSs) with large cyclotron effective masses (33–43m₀) 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.