Fig. 5: Gate tuning and reconfiguration of HShPs in twisted bilayer α-MoO3/graphene device.
From: Engineering shear polaritons in 2D twisted heterostructures
a Schematic of a twisted bilayer α-MoO3/graphene heterostructure. Ein and Eout denote the incident and scattered electric fields, respectively. VDS, drain-source voltage. VBG, back-gate voltage. b Calculated IFCs of HShPs for different Fermi energy EF show that gate tuning can be used to change the topology and direction of HShPs, transitioning from hyperbolic (yellow) to elliptic (blue). The top and bottom α-MoO3 layer thicknesses are d1 = 96 nm and d2 = 78 nm, respectively. The twist angle θ is 62°. The x axis is along the [100] direction of the top α-MoO3 layer. Experimental near-field images for HShPs at EF of 0 eV (c), −0.18 eV (d), −0.33 eV (e), −0.43 eV (f), and −0.51 eV (g), respectively. As the Fermi energy becomes more negative, the direction of maximal propagation of shear waves changes, along with their topology. h–l Experimental, and m–q simulated Fourier spectra, corresponding to (c–g). r The growing shear factor obtained for increasingly negative EF shows the gate-tuning induced enhanced asymmetry of HShPs, as demonstrated by both experiments (red dots) and simulations (blue dots).
