Figure 1

(a) Schematic representations of the IQHE in mono-, bi-, and trilayer graphene. The degeneracy of the zeroth Landau level (LL) is fourfold degenerate in graphene, eightfold degenerate in bilayer graphene, and twelvefold degenerate in trilayer graphene, leading to a sequence of Hall resistance plateaus shifted by $2h/e^2\Omega$. Inset: Raman spectrum of trilayer graphene (red or top curve) and monolayer graphene (black or bottom curve) measured on the same substrate. (b) Experimental IQHE in tri-, bi-, and monolayer graphene for equivalent carrier density $n=3.4\times {10}^{12}{\mathrm{cm}}^{-2}$ and similar mobility $\mu =1200{\mathrm{cm}}^2{\mathrm{V}}^{-1}·{\mathrm{s}}^{-1}$. The optical image of the trilayer graphene sample is shown in inset. As contact 1 was proven defective, a constant current of $i=1\mu \mathrm{A}$ is injected through contacts 2 and 4. The Hall resistance is measured between contacts 3 and 5.Reuse & Permissions

Figure 2

Ball-and-stick model for a $ABA$ and $ABC$-stacked trilayer graphene (top panel), theoretical Landau level structure (middle panel) and quantized Hall resistance (bottom panel) using: $V_{\mathrm{g}}=50\mathrm{V}$, $V_{\mathrm{CNP}}=-13.75\mathrm{V}$, $T=4.2\mathrm{K}$, $W_0=10\mathrm{meV}$ and $g=2$. In the middle panel, the solid and dashed curves indicate the Landau levels originating from valleys $K$ and $K^{\prime }$, respectively. Bottom panel : experimental (red line) and theoretical (black line) Hall resistance.Reuse & Permissions

Figure 3

(a) Longitudinal resistance as a function of carrier concentration at 4.2 K. (b) Hall resistance for various back-gate voltage in the vicinity of the CNP. Notice that the Hall resistance tends to vanish at $V_g\approx V_{\mathrm{CNP}}$ and very high magnetic field. For $V_g\gg V_{\mathrm{CNP}}$, the expected quantum Hall effect in the graphene trilayer is recovered.Reuse & Permissions