Magnetic and charge susceptibilities in the half-filled triangular lattice Hubbard model

TL;DR

This paper investigates magnetic and charge responses in the half-filled triangular Hubbard model using dual fermion methods, revealing persistent spin fluctuations and providing data relevant to neutron and electron-loss spectroscopy experiments.

Contribution

It introduces a dual fermion approach to analyze magnetic and charge susceptibilities across different phases of the model, connecting theoretical predictions with experimental observations.

Findings

Strong low-energy spin fluctuations at the K point in the insulating state

Persistence of spin fluctuations into the metallic phase at higher energies

Predictions for neutron and electron-loss spectroscopy measurements

Abstract

We study magnetic and charge susceptibilities in the half-filled two-dimensional triangular Hubbard model within the dual fermion approximation in the metallic, Mott insulating, and crossover regions of parameter space. In the \textcolor{black}{insulating state}, we find strong spin fluctuations at the K point at low energy corresponding to the \textcolor{black}{120$^{\circ}$} antiferromagnetic order. These spin fluctuations persist into the metallic phase and move to higher energy. We also present data for simulated neutron spectroscopy and \textcolor{black}{spin-lattice} relaxation times, and perform direct comparisons to inelastic neutron spectroscopy experiments on the triangular material Ba$_8$CoNb$_6$O$_{24}$ and to the relaxation times on $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$. Finally, we present charge susceptibilities in different areas of parameter space, which should correspond to momentum-resolved electron-loss spectroscopy measurements on triangular compounds.