A new noncollinear ferromagnetic Weyl semimetal with anisotropic anomalous Hall effect

TL;DR

This paper introduces CeAlSi as a novel noncentrosymmetric ferromagnetic Weyl semimetal with noncollinear magnetic order and anisotropic anomalous Hall effect, expanding the class of FM-WSMs with unique electromagnetic responses.

Contribution

It reports CeAlSi as the first noncentrosymmetric FM-WSM with noncollinear magnetism and tunable Weyl nodes, highlighting its anisotropic AHE and potential for device applications.

Findings

CeAlSi has noncentrosymmetric lattice and noncollinear FM order.

CeAlSi exhibits anisotropic anomalous Hall effect.

Large FM domains observed, promising for applications.

Abstract

A developing frontier in condensed matter physics is the emergence of novel electromagnetic responses, such as topological and anomalous Hall effect (AHE), in ferromagnetic Weyl semimetals (FM-WSMs). Candidates of FM-WSM are limited to materials that preserve inversion symmetry and generate Weyl crossings by breaking time-reversal symmetry. These materials share three common features: a centrosymmetric lattice, a collinear FM ordering, and a large AHE observed when the field is parallel to the magnetic easy-axis. Here, we present CeAlSi as a new type of FM-WSM, where the Weyl nodes are stabilized by breaking inversion symmetry, but their positions are tuned by breaking time-reversal symmetry. Unlike the other FM-WSMs, CeAlSi has a noncentrosymmetric lattice, a noncollinear FM ordering, and a novel AHE that is anisotropic between the easy- and hard-axes. It also exhibits large FM domains that are promising for both device applications and an interplay between the Weyl nodes and FM domain walls.