Origin of the turn-on temperature behavior in WTe2

A hallmark of materials with extremely large magnetoresistance (XMR) is the transformative turn-on temperature behavior: when the applied magnetic field $H$ is above certain value, the resistivity versus temperature $\ensuremath{\rho}(T)$ curve shows a minimum at a field dependent temperature ${T}^{*}$, which has been interpreted as a magnetic-field-driven metal-insulator transition or attributed to an electronic structure change. Here, we demonstrate that $\ensuremath{\rho}(T)$ curves with turn-on behavior in the newly discovered XMR material ${\mathrm{WTe}}_{2}$ can be scaled as $\text{MR}\ensuremath{\sim}{(H/{\ensuremath{\rho}}_{0})}^{m}$ with $m\ensuremath{\approx}2$ and ${\ensuremath{\rho}}_{0}$ being the resistivity at zero field. We obtained experimentally and also derived from the observed scaling the magnetic field dependence of the turn-on temperature ${T}^{*}\ensuremath{\sim}{(H\ensuremath{-}{H}_{c})}^{\ensuremath{\nu}}$ with $\ensuremath{\nu}\ensuremath{\approx}1/2$, which was earlier used as evidence for a predicted metal-insulator transition. The scaling also leads to a simple quantitative expression for the resistivity ${\ensuremath{\rho}}^{*}\ensuremath{\approx}2{\ensuremath{\rho}}_{0}$ at the onset of the XMR behavior, which fits the data remarkably well. These results exclude the possible existence of a magnetic-field-driven metal-insulator transition or significant contribution of an electronic structure change to the low-temperature XMR in ${\mathrm{WTe}}_{2}$. This work resolves the origin of the turn-on behavior observed in several XMR materials and also provides a general route for a quantitative understanding of the temperature dependence of MR in both XMR and non-XMR materials.