Tunneling measurements in graphene-hexagonal boron nitride-based heterostructures*

Van der Waals heterostructures is an emerging field involving the study of layered materials consisting of various crystalline atomic planes exfoliated from bulk crystals and then stacked, often by hand, in custom-made patterns. Vertical tunneling structures made out of such quasi-2D crystals are potentially very interesting and may provide a new playground to observe electron-electron interaction effects in graphene and related materials. In the present work, we report the fabrication and study of several such tunnel junctions, including metal-hexagonal boron nitride (hBN)-metal, metal-hBN-graphite and metal-hBN-graphene devices. Tunneling measurements done at low temperatures and high magnetic fields reveal interesting and distinct features in each of these designs.