Anisotropic giant magnetoresistance and Fermi surface topology in the layered compound YbBi2

Magnetoresistance in novel materials has been attracting ever-increasing attention since its mechanism is still the subject of intense debate and the physics behind these emergent phenomena remains a wild space to be explored. Here, we grow YbBi2 single crystals and study their anisotropic giant magnetoresistance and Fermi surface topology via de Haas-van Alphen oscillation and Hall resistivity measurements, electronic band structure calculations, and so on. A detailed analysis of the angle-dependent quantum oscillations reveals the presence of nontrivial topological electronic states and several cylindrical Fermi surface sheets extended along the b axis. Hall resistivity data suggest that multiple charge carriers participate in the transport, and electron and hole densities are nearly balanced. These findings are further confirmed by theoretical calculations. After checking several possible mechanisms, the giant magnetoresistance (∼1.2×103% at 14 T and 2 K) in YbBi2 is ascribed to the carrier compensation instead of topological protection and open orbits. Additionally, we also find that Fermi surface anisotropy serves as a key element for the angular magnetoresistance in this compound. Our studies show that YbBi2 can be not only a topologically nontrivial material, but also a prototype system to check familiar magnetoresistance mechanisms.