Fig. 2: Finite magnetic field thermopower and resistance measurements.
a Magnetic field dependence of measured thermopower at n/ns = + 0.03, − 0.002, − 0.03 at 1K, where ns is the carrier density (n) at full filling of the flat band. The inset shows the theoretically predicted thermopower for compensated semimetallic band. b Theoretically extracted normalized effective charge density (\(\frac{({n}_{e}-{n}_{h})}{({n}_{e}+{n}_{h})}\)) (ne(nh) being the electron(hole) density) as a function of n/ns. c 2D color plot of thermopower as a function of perpendicular magnetic field and n/ns at 1K. (d) Cartoon illustration of the (Etot × B) drift on the carriers in the limit when magnetic field (B) approaches BH (i.e at magnetic field where Hall angle θH → 90o). The Hall voltage along the y direction leads to an electric field EH, where ∣EH∣ ≫ ∣Ex∣ (Ex is the applied electric field) in the limit θH ≈ 90o. Electrons (labeled e) and holes (labeled h) both drift alongside in presence of crossed electric (Etot = Ex + EH ≈ EH) and magnetic field contributing additively to the heat current36. e 2D color plot of thermopower plotted over a wide range of density / n/ns (bottom axis / top axis) and magnetic field (divided by flux quanta Φ0) with red (yellow) dashed lines marking the landau levels emanating from n/ns = 0 ( − 1). f Resistance as a function of perpendicular magnetic field and n/ns at 20 mK. g Perpendicular magnetic field dependence of measured resistance at several n/ns at 1 K. The presence of semimetallic band is further reflected through metal-insulator transition of resistance versus temperature curve with increasing perpendicular magnetic field, as demonstrated in the inset.
