CrRhAs: a member of a large family of metallic kagome antiferromagnets

TL;DR

This paper investigates the magnetic properties of the metallic kagome compound CrRhAs, revealing complex interactions and unusual ground states driven by its electronic structure and magnetic couplings.

Contribution

It provides the first detailed model magnetic Hamiltonian for CrRhAs, highlighting the roles of long-range couplings and ring exchange in its magnetic behavior.

Findings

Dominant antiferromagnetic second nearest neighbor coupling

Unusual ground states with nearly isolated antiferromagnetic triangles

Connection to experimental observations of CrRhAs

Abstract

Kagome lattice materials are an important platform for highly frustrated magnetism as well as for a plethora of phenomena resulting from flat bands, Dirac cones and van Hove singularities in their electronic structures. We study the little known metallic magnet CrRhAs, which belongs to a vast family of materials that include $3d$, $4f$ and $5f$ magnetic elements, as well as numerous nonmagnetic metals and insulators. Using noncollinear spin density functional calculations (mostly spin spirals), we extract a model magnetic Hamiltonian for CrRhAs. While it is dominated by an antiferromagnetic second nearest neighbor coupling in the kagome plane, the metallic nature of the compound leads to numerous nonzero longer range couplings and to important ring exchange terms. We analyze this Hamiltonian and find unusual ground states which are dominated by nearly isolated antiferromagnetic triangles that adopt 120$^\circ$ order either with positive or with negative vector chirality. We discuss the connection to the few known experimental facts about CrRhAs. Finally, we give a brief survey of other interesting magnetic members of this family of kagome compounds.