Quantum Oscillations and Chiral Anomaly in a Bi_0.96Sb_0.04 Single Crystal

B_1-xSb_x alloys are of special significance in topological insulator research. Here we focus on the Bi_0.96Sb_0.04 alloy in which the conduction band edge just touches the valence band edge. Transport measurements show quantum oscillations in the longitudinal (Shubnikov–de Haas effect) and transverse magnetoresistance originating from a spheroidal Fermi surface pocket. Further investigation of the longitudinal magnetoresistance for the magnetic field parallel to the electrical current shows a small nonmonotonic magnetoresistance that is attributed to a competition of weak-antilocalization effects and a topological term related to the chiral anomaly.