The large unsaturated magnetoresistance of Weyl semimetals

The Weyl semimetal (WSM) is a novel topological gapless state with promises exotic transport due to chiral anomaly. Recently, a family of nonmagnetic WSM candidates including TaAs, NbAs, NbP etc is confirmed by first principle calculation and experiments. The TaAs family are reported to display the large unsaturated magnetoresistance (XMR), which have not yet been explained. Here, we give a theoretical calculation of XMR based on the extended effective-medium approach to Weyl semimetals. We predict the power law of XMR at high magnetic field and the "turn-on" magnetic field, which are well in agreement with experiments data. Furthermore, we investigate the $\theta$-dependence magnetoresistance and find the transition between the postive XMR and the negative magnetoresistance induced by chiral anomaly, which should be confirmed by further experiments.