Fig. 3.

Chiral-anomaly induced negative longitudinal MR. a MR data obtained along different field directions at 2 K show strong anisotropy in the transport properties. In all of the measurements, I//b in the 19.4 nm thick b-axis ribbon. b The field-dependent, negative and longitudinal MR induced by a chiral anomaly in b-axis ribbon. We note that the occurrence of the maximum negative MR at 89° rather that at 90° could be due to a misalignment when we glued the sample to the sample holder. c The longitudinal MR measured with θ = 87.5° at different temperatures. d The temperature-dependent resistivity of 19.4 nm thick a-axis and b-axis ribbon. The scale bar in the optical image is 5 μm. e Comparison of quantum oscillation in both ribbons with the magnetic field normal to the ribbon. f The absence of chiral-anomaly-induced negative MR in a-axis ribbon