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This study investigates charge ordering in triangular-lattice systems using the extended Hubbard model combined with dynamical mean-field theory (DMFT). The researchers mapped out a rich phase diagram featuring multiple distinct phases, including "pinball-liquid" phases driven either by charge transfer or Mott localization, as well as phase transitions that shift between discontinuous and continuous character depending on model parameters. A notable unexpected finding was the emergence of a small intermediate metallic phase on the electron-doped side of the phase diagram, which was not predicted by simpler approximation methods.
Why it matters
Understanding charge ordering in strongly correlated triangular-lattice systems is relevant to the design and interpretation of quantum materials, including frustrated magnets, transition metal dichalcogenides, and Moiré systems, where controlling electronic phases could advance quantum computing and energy applications.
arXiv:2605.18575v1 Announce Type: cross
Abstract: Triangular-lattice systems attract a lot of attention due to various frustration-induced and strongly correlated effects. Here, we focus on the charge-ordering phenomenon by means of investigation of the extended Hubbard model with dynamical mean-field theory (DMFT). By considering the intersite nearest-neighbor interaction we have found a very rich phase diagram that contains large number of features, phases, and phase transitions. Among them are pinball-liquid (PL) phases where we distinguish charge-transfer-driven and Mott-localization-driven PLs; phase transitions that change their order as model parameters evolve (from discontinuous to continuous); very strong particle-hole asymmetry. Various features of the phase diagram are found to be better understood by means of the simple mean-field approximation (MFA). Moreover, besides helping with interpretation of the phase diagram, the MFA results together with results for the atomic-limit model are found to be able to set rather good expectations on how the DMFT phase diagram should look like. Nevertheless, a few features were not expected and are found within the DMFT, such as a small-region intermediate metallic phase on an electron-doped side of the phase diagram.
Source: Charge order on a triangular lattice with Mott physics and arbitrary charge density