Fragment-orbital-dependent spin fluctuations in the single-component molecular conductor [Ni(dmdt)${}_2$]

Abstract

Motivated by recent nuclear magnetic resonance experiments, we calculated the spin susceptibility, Knight shift, and spin-lattice relaxation rate ($1/T_{1}T$) of the single-component molecular conductor [Ni(dmdt)${}_2$] using the random phase approximation in a multi-orbital Hubbard model describing the Dirac nodal line electronic system in this compound. This Hubbard model is composed of three fragment orbitals and on-site repulsive interactions obtained using ab initio many-body perturbation theory calculations. We found fragment-orbital-dependent spin fluctuations with the momentum $\text{q}$=$\text{0}$ and an incommensurate value of the wavenumber $\text{q}$=$\text{Q}$ at which a diagonal element of the spin susceptibility is maximum. The $\text{q}$=$\text{0}$ and $\text{Q}$ responses become dominant at low and high temperatures, respectively, with the Fermi-pocket energy scale as the boundary. We show that $1/T_{1}T$ decreases with decreasing temperature but starts to increase at low temperature owing to the $\text{q}$=$\text{0}$ spin fluctuations, while the Knight shift keeps monotonically decreasing. These properties are due to the intra-molecular antiferromagnetic fluctuations caused by the characteristic wave functions of this Dirac nodal line system, which is described by an $n$-band ($n\ge 3$) model. We show that the fragment orbitals play important roles in the magnetic properties of [Ni(dmdt)${}_2$].

References in corpus (16)

• Advanced capabilities for materials modelling with Quantum ESPRESSO
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Dirac materials
• Tilted anisotropic Dirac cones in quinoid-type graphene and alpha-(BEDT-TTF)_2I_3
• Classification of reflection symmetry protected topological semimetals and nodal superconductors
• Charge Ordering in alpha-(BEDT-TTF)2I3 by synchrotron x-ray diffraction
• Observation of an anisotropic Dirac cone reshaping and ferrimagnetic spin polarization in an organic conductor
• Anomalous Orbital Magnetism and Hall Effect of Massless Fermions in Two Dimension
• Electronic Properties Close to Dirac Cone in Two-Dimensional Organic Conductor $\alpha$-(BEDT-TTF)${}_2$I${}_3$
• Single-Component Molecular Metals as Multiband π-d Systems
• Correlation Effects on Charge Order and Zero-Gap State in the Organic Conductor α-(BEDT-TTF)2I3
• Spin excitations in the quasi-two-dimensional charge-ordered insulator $\alpha$-(BEDT-TTF)${}_2$I${}_3$ probed via ${}^{13}$C NMR
• Electronic States of Single-Component Molecular Conductors [M(tmdt)2]
• Multi-Orbital Molecular Compound (TTM-TTP)I_3: Effective Model and Fragment Decomposition
• Tight-Binding Model and Electronic Property of Dirac Nodal Line in Single-Component Molecular Conductor [Pt(dmdt)${}_2$]