Possible Spin-Density Wave on Fermi Arc of Edge State in Single-Component Molecular Conductors [Pt(dmdt)$_2$] and [Ni(dmdt)$_2$]

TL;DR

This study models single-component molecular conductors, revealing that Coulomb interactions induce edge spin-density waves on Fermi arcs, with magnetic properties tunable by minimal doping, advancing understanding of edge magnetism in these materials.

Contribution

The paper introduces a three-orbital tight-binding model and demonstrates the emergence of edge SDWs driven by Coulomb repulsion and Fermi arc nesting, with controllable magnetic structures.

Findings

Edge SDW is induced by Coulomb repulsion.

Magnetic structure can be tuned by small carrier doping.

Fermi arcs exhibit incommensurate nesting leading to SDW.

Abstract

We construct three-orbital tight-binding models describing single-component molecular conductors [Pt(dmdt)$_2$] and [Ni(dmdt)$_2$] using first-principles calculations. We show that [Ni(dmdt)$_2$] is a Dirac nodal line system with highly one-dimensional edge states at the (001) edge, similar to [Pt(dmdt)$_2$], as demonstrated in prior studies. To investigate possible edge magnetism, we calculate longitudinal and transverse spin susceptibilities using real-space-dependent random-phase approximation (RPA) in three-orbital Hubbard models in the presence of spin--orbit coupling. We find that the edge spin-density wave (SDW) is induced by the Coulomb repulsion and incommensurate nestings of the Fermi arcs. We also find that the magnetic structure of the edge SDW can be changed via extremely small carrier doping, which is controllable in molecular conductors.