Probing the gap of single layer WTe₂ by tunnel capacitance spectroscopy

Single layer WTe₂ displays a topological insulator state in addition to unexpected superconductivity and possible correlated effects at low temperatures. While early theoretical efforts predicted a trend towards gap formation due to spin-orbit coupling, surprising new experimental results suggest a potential many-body origin for the insulating gap observed in transport and spectroscopic measurements. While transport measurements only provide limited information about the density of states, tunnel capacitance spectroscopy provides detailed information about both thermodynamic and single particle properties of all electronic states, including those in the insulating gap. To further elucidate the origins of this gap, we probe these thermodynamic properties and spectroscopic signatures of the gap of WTe₂ embedded in a vertical tunneling geometry with capacitive sensing.