Colossal magnetoresistance and Fermi surface topology in the layered Zintl-phase compound YbA l2 S i2

Considerable attention has been devoted to CaAl2Si2-type Zintl-phase compounds for their intriguing physical properties, particularly the complex interplay between band structures and magnetism. Herein we grow high-quality single crystals of nonmagnetic YbAl2Si2 and examine the physical properties, including resistivity, magnetoresistance, angular magnetoresistance, Hall resistivity, and band structures. This compound shows metallic properties and Fermi-liquid behaviors. Its resistivity under magnetic fields increases as per Kohler rule, with normalized magnetoresistance curves merging into one, ruling out potential metal-insulator-like transitions. Colossal magnetoresistance is observed at low temperatures. Hall resistivity analysis categorizes this compound as an uncompensated semimetal. Its angle dependence of the magnetoresistance and quantum oscillation frequencies demonstrate an anisotropy ratio of ∼1.26 for the Fermi surface. Theoretical calculations corroborate these findings, mapping Fermi surfaces with three hole pockets and an electron pocket. Considering both the experimental and theoretical results, the colossal and angle-dependent magnetoresistance may be ascribed to unequal carrier densities coupled with large differences in carrier mobilities and Fermi-surface anisotropy, respectively. These results imply YbAl2Si2 is a promising candidate to study the crucial effect of electronic properties on its charge transport.