Magnetotransport properties of the topological semimetal SrAgBi

Abstract

Recently, the hexagonal compound SrAgBi has been theoretically predicted to host linearly dispersing type-II and nonlinearly dispersing type-IV Dirac fermions near the Fermi level. Here, we report the results of magnetotransport measurements performed on SrAgBi single crystals in the temperature range 2--300 K, with electric current flowing within the crystallographic $ab$ plane and magnetic field up to 9 T oriented along the $c$ axis. The electrical resistivity shows a metallic behavior, and an onset of filamentary like, type-II superconductivity below 2.9 K. The transverse magnetoresistance is positive and very small (approximately 4% at 5 K and 9 T). In weak fields and at low temperatures, it shows the existence of weak antilocalization effect, which signifies the presumed Weyl semimetallic character of SrAgBi. The Hall measurements show holes to be major charge carriers in the entire temperature range investigated. At 5 K, their density equals $\ensuremath{\sim}5.4\ifmmode\times\else\texttimes\fi{}{10}^{20}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\text{--}3}$ and their mobility is $\ensuremath{\sim}3.6\ifmmode\times\else\texttimes\fi{}{10}^{2}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}/(\mathrm{V}\phantom{\rule{0.16em}{0ex}}\mathrm{s})$. Based on the collected magnetotransport data, SrAgBi can be categorized as an uncompensated semimetal with the electrical properties describable using the simplistic single-band approach. The experimental results, in conjunction with the theoretical calculations, suggest that the topological surface states in SrAgBi are overshadowed by the large hole pocket which governs the transport behavior in this material.