Quasi-linear magnetoresistance and paramagnetic singularity in hypervalent bismuthide

Materials featuring hypervalent bismuth motifs have generated immense interest due to their extraordinary electronic structure and exotic quantum transport. In this study, we synthesized high-quality single crystals of La₃ScBi₅ characterized by one-dimensional hypervalent bismuth chains and performed a systematic investigation of the magnetoresistive behavior and quantum oscillations. The metallic La₃ScBi₅ exhibits a low-temperature plateau of electrical resistivity and quasi-linear positive magnetoresistance, with anisotropic magnetoresistive behaviors suggesting the presence of anisotropic Fermi surfaces. This distinctive transport phenomenon is perfectly elucidated by first-principles calculations utilizing the semiclassical Boltzmann transport theory. Furthermore, the nonlinear Hall resistivity pointed towards a multiband electronic structure, characterized by the coexistence of electron and hole carriers, which is further supported by our first-principles calculations. Angle-dependent de Haas-van Alphen oscillations are crucial for further elucidating its Fermiology and topological characteristics. Intriguingly, magnetization measurements unveiled a notable paramagnetic singularity at low fields, which might suggest the nontrivial nature of the surface states. Our findings underscore the interplay between transport phenomena and the unique electronic structure of hypervalent bismuthide La₃ScBi₅, opening avenues for exploring novel electronic applications.