Transport properties of the bulk state in bilayer WTe$_{\mathrm{2}}$

Three-dimensional WTe$_{\mathrm{2}}$ was recently reported to have a large, non-saturating magnetoresistance. Monolayer WTe$_{\mathrm{2}}$, on the other hand, was recently predicted to be a topologically nontrivial semimetal. However, we find that monolayer WTe$_{\mathrm{2}}$ encapsulated in h-boron nitride becomes insulating in the 2D bulk at temperatures below about 100 K, while the edge remains conducting, as in a topological insulator. In bilayer WTe$_{\mathrm{2}}$, we find that the 2D bulk behaves similarly to that in monolayer WTe$_{\mathrm{2}}$ but at lower temperatures (insulating below \textasciitilde 20 K). The edge conduction, however, is absent in the bilayer, providing the opportunity to study the bulk state without complications from the edge. By fabricating a Hall bar device in a bilayer, we can therefore determine the magnetoresistance and the Hall effect and their dependence on temperature and gate voltage.