  In this work, the magneto-resistance (MR) of ultra-thin WTe2/BN
heterostructures far away from electron-hole equilibrium is measured. The
change of MR of such devices is found to be determined largely by a single
tunable parameter, i.e. the amount of imbalance between electrons and holes. We
also found that the magnetoresistive behavior of ultra-thin WTe2 devices is
well-captured by a two-fluid model. According to the model, the change of MR
could be as large as 400,000%, the largest potential change of MR among all
materials known, if the ultra-thin samples are tuned to neutrality when
preserving the mobility of 167,000 cm2V-1s-1 observed in bulk samples. Our
findings show the prospects of ultra-thin WTe2 as a variable magnetoresistance
material in future applications such as magnetic field sensors, information
storage and extraction devices, and galvanic isolators. The results also
provide important insight into the electronic structure and the origin of the
large MR in ultra-thin WTe2 samples.
