The prediction of the quantum spin Hall effect in two-dimensional $\mathrm{ZrT}{\mathrm{e}}_5$ and $\mathrm{HfT}{\mathrm{e}}_5$ monolayers has generated considerable recent interest in these materials. In addition, Dirac points and chiral-anomaly-induced negative longitudinal magnetoresistance (MR) have been observed in $\mathrm{ZrT}{\mathrm{e}}_5$. Herein, we study the transport behavior of $\mathrm{HfT}{\mathrm{e}}_5$ single crystals in detail and find a large $(0.9\times {10}^4\%)$ out-of-plane transverse MR, which is among the highest for layered materials reported thus far. We also encounter a large linear in-plane transverse (magnetic field $\parallel c$, current $\parallel a)$ MR and discuss its possible origin. The mass anisotropy $(\gamma =5.4$ at 125 K) obtained by scaling angle-dependent MR data is consistent with the $\mathrm{HfT}{\mathrm{e}}_5$ elliptical Fermi surface.

• Received 12 May 2016
• Revised 20 December 2016

DOI:https://doi.org/10.1103/PhysRevB.95.155128