Quantum oscillations and anomalous angle-dependent magnetoresistance in the topological candidateAg3Sn

Abstract

Because of their unique electronic structure and peculiar physical properties, topological materials have attracted considerable attention in condensed matter physics. In both physics and material science, exploring materials with a topological state or Dirac fermions near the Fermi level is important. Here, we report the transport evidence of the topological state for ${\mathrm{Ag}}_{3}\mathrm{Sn}$. Under a high magnetic field, we observed clear Shubnikov--de Haas (SdH) oscillations with three major frequencies and relatively small effective masses. Our SdH quantum oscillation analyses reveal that the Berry phase of the $\ensuremath{\gamma}$ band is very close to the nontrivial value $\ensuremath{\pi}$; the nonzero Berry phase for the $\ensuremath{\alpha}$ band indicates the ${\mathrm{Ag}}_{3}\mathrm{Sn}$ alloy to be a possible topological material. Moreover, we performed angle-resolved magnetoresistance (MR) measurements. Note that MR displays an unusual angular dependence, which can be tuned from twofold to fourfold symmetry by temperature and field. This feature makes ${\mathrm{Ag}}_{3}\mathrm{Sn}$ a candidate for valleytronics.