Figure 1. Electric and magnetic field effect of channel resistivity in few-layer graphene.

(a) Resistivity versus external magnetic field (H) based on the theoretical prediction for a certain combination of carrier densities and mobilities in two effective channels, suggesting the possibility of very high magnetic field sensitivity at moderate magnetic fields. Case I: n₁=10¹¹ cm⁻², n₂=1.1 × 10¹¹ cm⁻², μ₁=20,000 cm² V⁻¹ s⁻¹, μ₂=1,000 cm² V⁻¹ s⁻¹; case II: n₁=8 × 10¹² cm⁻², n₂=1.1 × 10¹¹ cm⁻², μ₁=5,000 cm² V⁻¹ s⁻¹, μ₂=1,000 cm² V⁻¹ s⁻¹; and case III: n₁=10¹¹ cm⁻², n₂=1.1 × 10¹¹ cm⁻², μ₁=200,000 cm² V⁻¹ s⁻¹, μ₂=10,000 cm² V⁻¹ s⁻¹. (b) Optical micrograph of the fabricated four-layer graphene (Gr) on top of BN and SiO₂. The location of Gr is indicated by red dashed lines. (c) The voltage (V_sd) as a function of source-drain current (I_sd) at various gate voltages (V_G) suggesting an ohmic contact for Cr/Au electrodes on Gr. (d) The channel resistivity (ρ) as a function of V_G at 400 K. A magnetic field of 9 T is also applied normal to the Gr plane.