Quantum oscillations and transport evidence of topological bands in La3MgBi5 single crystals

In this work, we synthesized single crystals of ${\mathrm{La}}_{3}\mathrm{Mg}{\mathrm{Bi}}_{5}$ and systematically investigated their structure, magnetism, and transport properties. ${\mathrm{La}}_{3}\mathrm{Mg}{\mathrm{Bi}}_{5}$ belongs to the ${A}_{3}M{X}_{5}$ family (A = Ca-Ba or rare earth, M = transition materials or Mg, X = chalcogen or pnictogen) and has a quasi-one-dimensional structure. Our magnetic and magnetoresistance measurements show the presence of de Haas--van Alphen (dHvA) and Shubnikov--de Haas (SdH) oscillations. Analysis of these quantum oscillation spectra reveals two major oscillation frequencies (${F}_{\ensuremath{\alpha}}$, ${F}_{\ensuremath{\beta}}$) with corresponding light effective mass and the nearly \ensuremath{\pi} Berry phase for ${F}_{\ensuremath{\alpha}}$, suggesting the nontrivial band topology in ${\mathrm{La}}_{3}\mathrm{Mg}{\mathrm{Bi}}_{5}$, which is further supported by our first-principles calculations. Besides, ${\mathrm{La}}_{3}\mathrm{Mg}{\mathrm{Bi}}_{5}$ manifests a large nonsaturating magnetoresistance and a nonlinear Hall effect at low temperatures. Our results show that ${\mathrm{La}}_{3}\mathrm{Mg}{\mathrm{Bi}}_{5}$ is a topological nontrivial material and a member of the ${A}_{3}M{X}_{5}$ family exhibiting topological properties, providing a platform for further investigation of topological fermionic properties in this family.