Extended Data Fig. 2: The angle, temperature and field dependence of the SdH effect.
a, Oscillatory component of the PDO frequency, Δf, obtained after a 4th-order polynomial background subtraction from raw data at different tilt angles. The SdH effect is weaker in the field downsweeps (short-dashed lines) than in the upsweeps (solid lines), probably due to sample heating. b, Δf taken at θ = 10. 9∘ at different temperatures. The field-dependent cyclotron energies shown in Fig. 1d are obtained by fitting the frequency difference between adjacent peaks and valleys to the LK formula. Horizontal bars denote the peaks and valleys used for the fits in Fig. 1d. The inset displays the interval between spin-up and spin-down SdH peaks in inverse magnetic field, as a function of μ0H. If the effective mass and the g-factor are field independent, this value is expected be a constant (see Methods). c, PDO frequency measured up to 75 T in the Duplex Magnet; only the lowest pair of Landau levels, that is, N = 2±, are shown. The inset shows the small amplitude differences of N = 2± levels between T = 0.57 K and 1.51 K, suggesting a nondiverging quasiparticle mass up to at least 72 T. d, MR measured by the pulsed current technique (see Methods) in the Duplex magnet. A downward kink is observed at 68 T and coincides with the N = 2− sublevel. This slope change may imply a crossover to an unknown high-field state in YbB12.
