Graphite Gate induced Quantum Oscillations in 2D Insulators

Recently, Wang et al. [1] reported magnetoresistance (MR) oscillations near the insulating state of monolayer WTe₂ encapsulated between thin hexagonal boron nitride (hBN) dielectrics (< 10 nm) and top and bottom graphite gates. They interpreted the results as evidence for charge-neutral fermions, engendering further theoretical proposals to explain the results. However, we demonstrate a capacitive mechanism by which MR oscillations in the sample are generated by oscillations of density of states in the graphite gate. We measure simultaneously resistances in graphite gate and monolayer WTe₂ and find oscillations in resistance coincide. In addition, we demonstrate ubiquity of MR in various 2D materials, including bilayer WTe₂, angle-aligned MoTe₂/WSe₂ heterobilayers and Bernal-stacked bilayer graphene. Furthermore, quantitative measurement on bilayer graphene reveals a 180-degree phase shift in the MR oscillations between slightly electron and hole doped bilayer graphene, in consistent with our proposed capacitive mechanism.

 

[1] Wang, et al., Nature 589, 225–229 (2021).