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. 2011 Dec 6;2:575. doi: 10.1038/ncomms1586

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Copyright © 2011, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.

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Main panel: Landau level index N versus 1/B plotted for selected values of gate voltage, corresponding to different concentrations of holes (red symbols) and electrons (blue symbols). According to the relation characteristic for massless Dirac fermions, , where n is the density of charge carriers (electrons or holes), whereas for normal fermions . Therefore, looking at how N extrapolates for allows us to discriminate between massless Dirac and normal fermions. The continuous lines are linear least square fits to the data . They show that as ,N extrapolates to close to −1/2 as expected for massless Dirac fermions. The inset shows the extrapolation value (b) obtained by least square fitting for ~20 different values of gate voltage (in the region with Vg in between ~−40 and +15 V, the oscillations are not sufficiently pronounced to perform the analysis). The data show that b fluctuates close to −1/2 (and not around 0). Consistently, the average of b over gate voltage is ‹b›=−0.4±0.1.

Inline graphic — Main panel: Landau level index N versus 1/B plotted for selected values of gate voltage, corresponding to different concentrations of holes (red symbols) and electrons (blue symbols). According to the relation characteristic for massless Dirac fermions, , where n is the density of charge carriers (electrons or holes), whereas for normal fermions . Therefore, looking at how N extrapolates for allows us to discriminate between massless Dirac and normal fermions. The continuous lines are linear least square fits to the data . They show that as ,N extrapolates to close to −1/2 as expected for massless Dirac fermions. The inset shows the extrapolation value (b) obtained by least square fitting for ~20 different values of gate voltage (in the region with Vg in between ~−40 and +15 V, the oscillations are not sufficiently pronounced to perform the analysis). The data show that b fluctuates close to −1/2 (and not around 0). Consistently, the average of b over gate voltage is ‹b›=−0.4±0.1.