Tight-Binding Model and Electronic Property of Dirac Nodal Line in Single-Component Molecular Conductor [Pt(dmdt)₂]

Abstract

Motivated by the recent discovery of Dirac nodal line in the single-component molecular conductor [Pt(dmdt) 2 ], we propose a three-orbital tight-binding model based on the Wannier fitting of the first-principles calculation, and address the problems of edge states, topological properties and magnetic susceptibility. We find that logarithmic peaks of the local density of states emerge near the Fermi energy, owing to pseudo-one-dimensional edge states that appear between the Dirac nodal lines. Magnetic susceptibility calculated in our model can explain the experimental result at a high temperature. In the presence of a realistic spin-orbit coupling, we show that [Pt(dmdt) 2 ] is a topological nodal line semimetal with isolated electron and hole pockets.

The quest for single component molecular metals within neutral transition metal complexes

“…14 More recently some SCMM and conductors were better described as Dirac electron systems (Fig. 2), [30][31][32][33][34] which may be seen as a very particular situation of a crossing band structure. In a Dirac electron system, the HOMO and LUMO bands cross at Dirac points, at variance with the characteristic gap opening in the crossing band structure.…”

“…The band calculations indicate that [Pt(dmdt) 2 ] is an ambient-pressure molecular Dirac electron system, also described as a nodal line semimetal. 32,34 Two other reported examples were [Ni(chdt) 2 ] (chdt: cyclohexenotetrathiafulvalenedithiolate) and [Ni(eodt) 2 ] (eodt: ethylenedioxytetrathiafulvalenedithiolate) (Chart 3), with s RT measured on compressed pellets ranging from 1 to 10 S cm À1 . 14,20,50 In the case of [Ni(eodt) 2 ], the resistivity decreases until 120 K, suggesting a metallic behaviour, but then it increases slowly, although retaining a reasonably conductivity at 0.6 K. 14,20,50 The following example was prepared aiming at obtaining neutral complexes more soluble in common organic solvents, whereby their molecular structure contains solubilizing chains or polar groups.…”

Possible Spin-Density Wave on Fermi Arc of Edge State in Single-Component Molecular Conductors [Pt(dmdt)2] and [Ni(dmdt)2]

“…There are a variety of Dirac nodal line/ring systems, such as graphite, 11 transition-metal monophosphates, 34 Cu3N, 35 antiperovskites, 36 perovskite iridates, 37 hexagonal pnictides CaAgX (X = P, As), 38 and singlecomponent molecular conductors [Pd(dddt) 2 ] 39-46 and [Pt(dmdt) 2 ]. 47,48 Dirac nodal line/ring systems exhibit novel electronic properties that differ from those of two- * kawamura@s.phys.nagoya-u.ac.jp dimensional systems, such as flat Landau levels, 49 the Kondo effect, 50 long-range Coulomb interaction, 51 and quasi-topological electromagnetic responses 52 .…”

“…7-10 Using a three-orbital tightbinding model based on density functional theory (DFT) calculations, we also discovered an extremely flat edge state that is topologically assigned on a specific surface of [Pt(dmdt) 2 ]. 48 The local density of state (LDOS) at that specific edge has logarithmic peaks and huge values near the Fermi energy. This result strongly suggests magnetic instability at that specific edge.…”

Nodal-line semimetal HMTSF-TCNQ: Anomalous orbital diamagnetism and charge density wave

“…A charge density wave (CDW) in topological bands induces fascinating phenomena, such as the threedimensional Hall effect [1] and axionic CDW phase [2], which have recently generated considerable research interest. A CDW is a quantum phase that is typical of quasi-one-dimensional organic conductors, and the topological properties of organic materials have become more extensively researched in the last two decades [3][4][5][6][7][8][9][10][11]. Organic materials that possess topological properties have the potential for novel phenomena that originate from the interplay between their topological bands and the CDW.…”