A Weyl-$\mathrm{Z}_2$ semimetal from holography

TL;DR

This paper develops effective field theories and holographic models for Weyl-$\mathrm{Z}_2$ semimetals, revealing their topological phase transitions characterized by anomalous transport parameters and exploring the effects of strong interactions.

Contribution

It introduces a holographic realization for strongly coupled Weyl-$\mathrm{Z}_2$ semimetals and analyzes their topological phase transitions and anomalous transport properties.

Findings

Topological phase transition characterized by anomalous Hall conductivities.

Nonzero anomalous transport parameters in the Weyl-$\mathrm{Z}_2$ semimetal phase.

Different behaviors of anomalous transport coefficients in holographic models.

Abstract

We present effective field theories for the weakly coupled Weyl-$\mathrm{Z}_2$ semimetal, as well as the holographic realization for the strongly coupled case. In both cases, the anomalous systems have both the chiral anomaly and the $\mathrm{Z}_2$ anomaly and possess topological quantum phase transitions from the Weyl-$\mathrm{Z}_2$ semimetal phases to partly or fully topological trivial phases. We find that the topological phase transition is characterized by the anomalous transport parameters, i.e. the anomalous Hall conductivity and the $\mathrm{Z}_2$ anomalous Hall conductivity. These two parameters are nonzero at the Weyl-$\mathrm{Z}_2$ semimetal phase and vanish at the topologically trivial phases. In the holographic case, the different behavior between the two anomalous transport coefficients is discussed. Our work reveals the novel phase structure of strongly interacting Weyl-$\mathrm{Z}_2$ semimetal with two pairs of nodes.