Hydrostatic pressure as a tuning knob for graphene heterostructures

Assembling atomically thin van der Waals crystals into a heterostructure can result in the emergence of new materials properties owing to the interactions between the stacked layers. Hydrostatic pressure provides a valuable control knob over these emergent properties, as it reduces the interlayer spacing between neighboring crystals and thus enhances their interlayer electronic coupling. Although pressure has been used previously in a small handful of experiments aimed at controlling correlated states in twisted graphene and manipulating the layer magnetism of CrI₃, it remains a challenging experiment to perform owing to a number of technical roadblocks. Here, we will discuss our ongoing efforts to develop new, simplified experimental schemes to turn pressure into a routine tuning knob that can be widely and easily used to study and control vdW heterostructure devices. In particular, we have designed a custom printed circuit board (PCB) for sample mounting compatible with conventional wire bonding rather than delicate hand-pasting schemes. The PCB acts as a connection terminal that routes 16 wires to the device within a small sample space of 3 mm diameter. The sample mounting and wiring scheme is compatible with a commercially available piston-cylinder pressure cell. We will report the status of ongoing work enabled by these efforts, including the investigation of various twisted and untwisted graphene-based systems under pressure.