Altermagnetism, Kagome Flat Band, and Weyl Fermion States in Magnetically Intercalated Transition Metal Dichalcogenides

TL;DR

This paper predicts that magnetically intercalated transition metal dichalcogenides can host altermagnetism, flat bands, and Weyl fermions, offering a versatile platform for topological and spintronic applications based on first-principles calculations.

Contribution

It identifies new altermagnetic candidates in intercalated TMDs and elucidates their magnetic, topological, and electronic properties through first-principles analysis.

Findings

Discovery of altermagnetic behavior in selected TMDs.

Emergence of Weyl nodes and Fermi arc surface states.

Presence of flat bands from kagome-like sublattice formation.

Abstract

Altermagnetic (AM) compounds have recently emerged as a promising platform for realizing unconventional quantum phases, enabled by their unique spin-split band structure at zero net magnetization. Here, we present a first-principles investigation of magnetically intercalated transition metal dichalcogenides (TMDs) of the form XY$_4$Z$_8$ (X $=$ Mn, Fe, Co, Ni, Cr, or V; Y $=$ Nb or Ta; and Z $=$ Se or S), identifying a subset of new versatile AM candidates. Our results establish a direct correlation between interatomic geometry, quantified by the ratio of interlayer to intralayer spacing, and the selection of magnetic ground states. Systems with A-type antiferromagnetic order exhibit momentum-dependent spin splitting consistent with AM behavior. Crucially, the combination of the AM spin-splitting and the spin-orbit coupling leads to the emergence of Weyl nodes together with the corresponding topological Fermi arc surface states. Moreover, we identify flat bands near the Fermi level that originate from the intercalant-induced formation of an effective kagome-like sublattice in the TMD layer. These results collectively establish magnetically intercalated TMDs as a promising platform for engineering altermagnetism, flat bands, and Weyl fermions within a single material family, facilitating the development of topological and spintronic applications.