Magnetic field tuning of the valley population in the Weyl phase of Nd$_2$Ir$_2$O$_7$

TL;DR

This study demonstrates how applying a magnetic field to Nd$_2$Ir$_2$O$_7$ can control the valley population in its Weyl phase by inducing charge pockets, revealing a new way to manipulate topological electronic states.

Contribution

It shows that a modest magnetic field can tune valley populations in a Weyl semimetal through charge compensation, a novel control mechanism.

Findings

A magnetic field of a few teslas creates charge pockets of holes and electrons.

Valley population can be tuned with the magnetic field.

Charge compensation occurs in different momentum space regions.

Abstract

The frustrated magnet Nd$_2$Ir$_2$O$_7$, where strong correlations together with spin-orbit coupling play a crucial role, is predicted to be a Weyl semimetal and to host topological pairs of bulk Dirac-like valleys. Here we use an external magnetic field to manipulate the localized rare earth 4f moments coupled to the 5d electronic bands. Low energy optical spectroscopy reveals that a field of only a few teslas suffices to create charge compensating pockets of holes and electrons in different regions of momentum space, thus introducing a valley population shift that can be tuned with the field.