Momentum-Resolved Planar Tunneling Spectroscopy of Twisted Graphene Heterostructures

Directly measuring a material’s band structure remains challenging and costly. While ARPES offers momentum-resolved access to occupied states, it is limited by surface sensitivity, the inability to probe unoccupied bands, and requires ultra-high vacuum systems. We present a planar tunneling approach for momentum-resolved spectroscopy of twisted graphene heterostructures. This technique directly probes a restricted slice of the band structure in a solid-state device that is both tunable and compact. Two independently gated two-dimensional layers are separated by an atomically thin insulating barrier. By varying gate voltages and interlayer bias, we align the probe and sample dispersions, allowing tunneling only when energy and in-plane momentum are conserved. Differential resistance measured as a function of electrostatic and magnetic tuning reconstructs the band structure, offering a new route to study flat-band formation and correlated states in moiré systems.