Anomalous conductivity tensor in the Dirac semimetal Na3Bi

Na3Bi is a Dirac semimetal with protected nodes that may be sensitive to the breaking of time-reversal invariance in a magnetic field B. We report experiments which reveal that both the conductivity and resistivity tensors exhibit robust anomalies in B. The resistivity rho(xx) is B-linear up to 35T, while the Hall angle exhibits an unusual profile approaching a step function. The conductivities sigma(xx) and sigma(xy) share identical power-law dependences at large B. We propose that these significant deviations from conventional transport result from an unusual sensitivity of the transport lifetime to B. The transport features are compared with those in Cd3As2. editor's choice Copyright (C) EPLA, 2016