  We report on electronic transport measurements of electrostatically gated
nano-devices of the semimetal WTe\textsubscript{2}. High mobility metallic
behavior is achieved in the 2D limit by encapsulating thin flakes in an inert
atmosphere. At low temperatures, we find that a large magnetoresistance can be
turned on and off by electrostatically doping the system between a semimetallic
state and an electron-only metallic state, respectively. We confirm the nature
of the two regimes by analyzing the magnetoresistance and Hall effect with a
two-carrier model, as well as by analysis of Shubnikov-de Haas oscillations,
both of which indicate depletion of hole carriers via the electrostatic gate.
This confirms that semiclassical transport of two oppositely charged carriers
accurately describes the exceptional magnetoresistance observed in this
material. Finally, we also find that the magnetoresistance power law is
sub-quadratic and density-independent, suggesting new physics specifically in
the semimetallic regime.
