Charge orders in organic charge-transfer salts

  • Motivated by recent experimental suggestions of charge-order-driven ferroelectricity in organic charge-transfer salts, such as κ-(BEDT-TTF)2Cu[N(CN)2]Cl, we investigate magnetic and charge-ordered phases that emerge in an extended two-orbital Hubbard model on the anisotropic triangular lattice at 3/4 filling. This model takes into account the presence of two organic BEDT-TTF molecules, which form a dimer on each site of the lattice, and includes short-range intramolecular and intermolecular interactions and hoppings. By using variational wave functions and quantum Monte Carlo techniques, we find two polar states with charge disproportionation inside the dimer, hinting to ferroelectricity. These charge-ordered insulating phases are stabilized in the strongly correlated limit and their actual charge pattern is determined by the relative strength of intradimer to interdimer couplings. Our results suggest that ferroelectricity is not driven by magnetism, since these polar phases can be stabilized also without antiferromagnetic order and provide a possible microscopic explanation of the experimental observations. In addition, a conventional dimer-Mott state (with uniform density and antiferromagnetic order) and a nonpolar charge-ordered state (with charge-rich and charge-poor dimers forming a checkerboard pattern) can be stabilized in the strong-coupling regime. Finally, when electron–electron interactions are weak, metallic states appear, with either uniform charge distribution or a peculiar 12-site periodicity that generates honeycomb-like charge order.

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Metadaten
Author:Ryui KanekoORCiD, Luca F. TocchioORCiD, Roser ValentíORCiDGND, Federico BeccaORCiDGND
URN:urn:nbn:de:hebis:30:3-365698
DOI:https://doi.org/10.1088/1367-2630/aa887b
ArXiv Id:http://arxiv.org/abs/1705.08915
Parent Title (English):New journal of physics
Document Type:Article
Language:English
Year of Completion:2017
Date of first Publication:2017/10/25
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2017/10/29
Volume:19
Issue:103033
Page Number:15
Note:
Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
HeBIS-PPN:424198797
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Sammlungen:Universitätspublikationen
Open-Access-Publikationsfonds:Physik
Licence (German):License LogoCreative Commons - Namensnennung 3.0