Quantum Hall effects in a Weyl Semi-Metal: possible application in pyrochlore Iridates

TL;DR

This paper explores quantum Hall effects in Weyl semi-metals, specifically in pyrochlore Iridates, highlighting potential experimental signatures like anomalous Hall effects and charge density waves to identify this novel topological phase.

Contribution

It introduces a general formula for anomalous Hall coefficients in Weyl semi-metals and discusses two novel quantum effects induced by magnetic fields in pyrochlore Iridates.

Findings

Pressure-induced anomalous Hall effect predicted

Magnetic field induces charge density wave at Weyl node wavevector

Proposed effects are experimentally detectable

Abstract

There have been lots of interest in pyrochlore Iridates A2Ir2O7 where both strong spin-orbital coupling and strong correlation are present. A recent LDA calculation suggests that the system is likely in a novel three dimensional topological semi-metallic phase: a Weyl semi-metal. Such a system has zero carrier density and arrives at the quantum limit even in a weak magnetic field. In this paper we discuss two novel quantum effects of this system in a magnetic field: a pressure-induced anomalous Hall effect and a magnetic field induced charge density wave at the pinned wavevector connecting Weyl nodes with opposite chiralities. A general formula of the anomalous hall coefficients in a Weyl semi-metal is also given. Both proposed effects can be probed by experiments in the near future, and can be used to detect the Weyl semi-metal phase.