Figure 1: Basic electrical transport properties of graphene-on-WS2 heterostructure at 250 mK.
From: Strong interface-induced spin–orbit interaction in graphene on WS2
(a) Optical microscope image of one of our devices, with multiple contacts in a Hall-bar geometry (scale bar, 10 μm). (b,c) Schematic cross-section of the device illustrating where charge is accumulated on varying Vg below and above ∼8 V (b and c, respectively). Owing to the presence of the n-doped WS2 substrate, charges are accumulated in graphene only for Vg lower than ∼8 V (the precise value slightly varies from sample to sample, depending on the doping level of the WS2 substrate.). (d) The conductivity (σ) of the device varies linearly with Vg, below ∼8 V, and saturates for larger Vg values (shadow area). The green dots mark the ranges of Vg (I: 0–5 V; II: −10 to −15 V; and III: −25 to −30 V) used to perform ensemble averages of the device magnetoconductance. (The inset shows Shubnikov-de Hass oscillation in the longitudinal resistance Rxx originating from the half-integer quantum-Hall effect characteristic of Dirac fermions, with the black regions corresponding to Rxx minima that occur at values of filling factor |ν|=|nh/eB|=4 × (N+1/2), with N being integer) (e–g) Fully developed half-integer quantum-Hall effect with vanishing Rxx (black curve) and quantized Rxy (red curve) observed at different values of Vg=0, −11.5 and −28 V (from e–g) within the region I, II and III (indicated in d).
