Transition-metal dichalcogenides (${\mathrm{WTe}}_2$ and ${\mathrm{MoTe}}_2$) have recently drawn much attention, because of the nonsaturating extremely large magnetoresistance (XMR) observed in these compounds in addition to the predictions of likely type-II Weyl semimetals. Contrary to the topological insulators or Dirac semimetals where XMR is linearly dependent on the field, in ${\mathrm{WTe}}_2$ and ${\mathrm{MoTe}}_2$ the XMR is nonlinearly dependent on the field, suggesting an entirely different mechanism. Electron-hole compensation has been proposed as a mechanism of this nonsaturating XMR in ${\mathrm{WTe}}_2$, while it is yet to be clear in the case of ${\mathrm{MoTe}}_2$ which has an identical crystal structure of ${\mathrm{WTe}}_2$ at low temperatures. In this Rapid Communication, we report low-energy electronic structure and Fermi surface topology of ${\mathrm{MoTe}}_2$ using angle-resolved photoemission spectrometry (ARPES) technique and first-principles calculations, and compare them with that of ${\mathrm{WTe}}_2$ to understand the mechanism of XMR. Our measurements demonstrate that ${\mathrm{MoTe}}_2$ is an uncompensated semimetal, contrary to ${\mathrm{WTe}}_2$ in which compensated electron-hole pockets have been identified, ruling out the applicability of charge compensation theory for the nonsaturating XMR in ${\mathrm{MoTe}}_2$. In this context, we also discuss the applicability of other existing conjectures on the XMR of these compounds.

• Received 2 February 2017

DOI:https://doi.org/10.1103/PhysRevB.95.241105