Fig. 2: Electric field-dependent energy gap extraction from DMG Landau level spectroscopy.
From: Direct probing of energy gaps and bandwidth in gate-tunable flat band graphene systems
a Zoom-in Landau fan diagrams of the white dashed rectangular regions in Fig. 1f. Clear Dirac LLs of the DMG are indicated by red and blue dashed lines and \({{{\mathrm{L}}}}{{{{\mathrm{L}}}}}_{N}^{D}\). The interval between LLs changes linearly with \(\sqrt{B}\). b The error bars of the chemical potential are derived from fitting the full-width half maximum (FWHM) of the high longitudinal resistance Rxx peak at points A and B, which are fitted to a Gaussian function. The ± σ are error edges of the corresponding chemical potentials. c The CNP gap (ΔCNP) of the BG extracted from different LLs of DMG. ΔCNP is the change of chemical potential along the gap. Since the error bars are derived from the broadening of Landau levels (LLs), the resolution of the experiments can be improved by using LLs with narrower bandwidths. The top axis BLL−B tracks the magnetic field of point B for every LL with index N. d Gap evolution as a function of D for Device_A1 (22°) and Device_A2 (27°). The overlap of blue and red dots demonstrates the consistency of the gap extracted from different LLs, which increases with increasing \(\left\vert D\right\vert\). The difference in Coulomb potential between two layers of BG induces a small gap at zero displacement field. e–g Landau Level spectroscopy at different D. The yellow dashed line indicates the kink of the first LL of the DMG. The gap completely closes at a small positive electric field D3.
