Tunable chirality of noncentrosymmetric magnetic Weyl semimetals

TL;DR

This paper demonstrates how breaking time-reversal and inversion symmetry in certain Weyl semimetals allows control over their net chirality by tilting magnetization, overcoming previous experimental limitations.

Contribution

It introduces a method to control Weyl fermion chirality in noncentrosymmetric magnetic Weyl semimetals through magnetization tilt.

Findings

Certain RMC2 compounds are Weyl semimetals.

Magnetization tilt can stabilize an odd number of Weyl nodes.

The net chirality sign depends on tilt direction.

Abstract

Even if Weyl semimetals are characterized by quasiparticles with well-defined chirality, exploiting this experimentally is severely hampered by Weyl lattice-fermions coming in pairs with opposite chirality, typically causing the net chirality picked up by experimental probes to vanish. Here we show this issue can be circumvented in a controlled manner when both time-reversal- and inversion- symmetry are broken. To this end, we investigate chirality-disbalance in the carbide family RMC$_2$ (R a rare-earth and M a transition metal), showing several members to be Weyl semimetals. Using the noncentrosymmetric ferromagnet NdRhC$_2$ as an illustrating example, we show that an odd number of Weyl nodes can be stabilized at its Fermi surface by properly tilting its magnetization. The tilt direction determines the sign of the resulting net chirality, opening up a simple route to control it.