Considering the Landau quantization and chiral anomaly, we develop a semiclassical theory of the positive longitudinal magnetoconductivity (LMC) of a Weyl semimetal induced by the chiral anomaly in an ac driving electric field. We find that for low angular frequencies, the anomalous LMC behaves in the same manner as in the dc case. However, the LMC decreases rapidly to zero with increasing the angular frequency of the electric field to be above a critical frequency, which is equal to the inverse of the intervalley relaxation time. With further increasing the frequency, the zero-magnetic-field conductivity diminishes above a critical frequency, which is equal to the inverse of the intravalley relaxation time. The two distinct transitions might be observed experimentally, so that the intervalley and intravalley relaxation times can be determined directly, which are considered to be two key parameters controlling the anomalous positive LMC effect in existing theories.

中文翻译：

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交流电场中Weyl半金属的异常正纵向磁导率的跃迁

考虑到Landau量化和手性异常，我们开发了一个半经典理论，即在交流驱动电场中由手性异常引起的Weyl半金属的正纵向磁导率（LMC）。我们发现，对于低角频率，异常LMC的行为与直流情况下的行为相同。但是，随着电场角频率增加到临界频率以上，LMC迅速减小到零，这等于间隔时间的倒数。随着频率的进一步增加，零磁场电导率在临界频率以上减小，该临界频率等于谷内弛豫时间的倒数。可以通过实验观察到这两个不同的过渡，