Melting of Domain Wall in Charge Ordered Dirac Electron of Organic Conductor α-(BEDT-TTF)<sub>2</sub>I<sub>3</sub>

Ohki, Daigo; Matsuno, Genki; Omori, Yukiko; Kobayashi, Akito

doi:10.7566/jpsj.87.054703

Cited by 7 publications

(15 citation statements)

References 52 publications

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“…Already introduced as the metalto-insulator transition temperature, T * also defines a phase boundary between the massless Dirac phase (with gapless Dirac cones) and the (charge-ordered) massive Dirac phase (with gapped Dirac cones). T DW , which coincides with T * , gives the energy scale for forming a single domain wall determined from the temperature where the domain-wall width W D diverges [15,17], and T M represents a merging transition of two gapped Dirac cones [4,5,15,16,[19][20][21][22][23]. The fact that we have T * = T DW directly supports the notion that the domain wall only appears in the charge-ordered state and disappears in the massless Dirac phase.…”

Section: A Local Electronic Structures and The Massive Dirac Electrosupporting

confidence: 73%

“…Finally, let us show that an emergent gapless state naturally appears on the the domain wall in the above model [15][16][17]. Figures 2(a) and (b) show the mean-field energy eigenvalue E ν (k a ) around the Fermi level at the transition temperature to the charge-ordered state (hereafter referred to as T * ) for the (AA -BC) asymmetricand (AA -AA ) symmetric-edge patterns, respectively.…”

Section: A Models and Summary Of Previous Studies: Emergent Domain Wmentioning

confidence: 98%

“…1(c)]. The interaction parameters are set to literature-accepted values U = 0.4 eV and V b = 0.05 eV [15][16][17], and, again, V a is the control parameter of the model. The third term in H int [Eq.…”

Section: A Models and Summary Of Previous Studies: Emergent Domain Wmentioning

confidence: 99%

“…To have a better understanding of this phase diagram, it is informative to focus on the evolution of the electronic state at low temperature as a function of V a . As one increases V a , there is first a transition from the massless Dirac phase to the massive Dirac phase at V c a = 0.197 (at T = 0) occurring simultaneously with the charge ordering [15][16][17]. Upon further increasing V a , the merging transition takes place at V c2 a = 0.211 (at T = 0.0005) where the system changes from the (charge-ordered) massive Dirac state (V c2 a > V a > V c a ) to the charge-ordered state with no Dirac cones (V a > V c2 a ) (As we mentioned previously, the valley Chern number changes from a finite value to zero across this transition [15], but in both phases metallic bound states exist along the domain wall).…”

Section: A Local Electronic Structures and The Massive Dirac Electromentioning

confidence: 99%

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Domain wall conductivity with strong Coulomb interaction of two-dimensional massive Dirac electrons in the organic conductor α−(BEDT−TTF)2I3

2019

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Motivated by the results of recent transport and optical conductivity studies, we propose a semiinfinite two-dimensional lattice model for interacting massive Dirac electrons in the pressurized organic conductor α-(BEDT-TTF)2I3, and address the problem of domain wall conductivity in a charge-ordered insulating phase under realistic experimental conditions. Using the extended Hubbard model at a mean field level, we present results of extensive numerical studies around the critical region of the model, reporting on the resistivity and optical conductivity calculated by means of the Nakano-Kubo formula. We find that the activation gap extracted from the resistivity data can be much smaller than the optical gap in the critical region, which is induced by metallic conduction along an one-dimensional domain wall emerging at the border of two charge-ordered ferroelectric regions with opposite polarizations. The data are consistent with the observed transport gap in real α-(BEDT-TTF)2I3 samples that is reduced remarkably faster than the optical gap upon suppressing charge order with pressure. Our optical conductivity also reveals an additional shoulder-like structure at low energy inside the gap, which is argued to be directly relevant to the metallic bound states residing on the domain wall. arXiv:1904.03884v2 [cond-mat.mes-hall]

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Section: A Local Electronic Structures and The Massive Dirac Electrosupporting

confidence: 73%

Section: A Models and Summary Of Previous Studies: Emergent Domain Wmentioning

confidence: 98%

Section: A Models and Summary Of Previous Studies: Emergent Domain Wmentioning

confidence: 99%

Section: A Local Electronic Structures and The Massive Dirac Electromentioning

confidence: 99%

See 2 more Smart Citations

Domain wall conductivity with strong Coulomb interaction of two-dimensional massive Dirac electrons in the organic conductor α−(BEDT−TTF)2I3

2019

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“…They also address the problem of domain wall conductivity in a charge-ordered insulating phase and can explain the discrepancy of a small energy gap extracted from resistivity data [139] compared to the optical gap [163] by metallic conduction along a one-dimensional domain wall emerging at the border of two charge-ordered ferroelectric regions with opposite polarizations. With increasing intersite interaction V , a transition from the massless Dirac phase to the massive Dirac phase occurs simultaneously with the charge ordering [248][249][250]. Upon further increasing V , the system changes from the charge-ordered massive Dirac state to the charge-ordered state with no Dirac cones.…”

Section: Domain Wallsmentioning

confidence: 99%

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Dressel

Tomić

2020

Advances in Physics

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This review provides a perspective on recent developments and their implications for our understanding of novel quantum phenomena in the physics of two-dimensional organic solids. We concentrate on the phase transitions and collective response in the charge sector, the importance of coupling of electronic and lattice degrees of freedom and stress an intriguing role of disorder. After a brief introduction to low-dimensional organic solids and their crystallographic structures, we focus on the dimensionality and interactions and emergent quantum phenomena. Important topics of current research in organic matter with sizeable electronic correlations are Mott metal-insulator phase transitions, charge order and ferroelectricity. Highly frustrated two-dimensional systems are established model compounds for studying the quantum spin liquid state and the competition with magnetic long-range order. There are also unique examples of quantum disordered state of magnetic and electric dipoles. Representative experimental results are complemented by current theoretical approaches.

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Interacting chiral electrons at the 2D Dirac points: a review

Hirata¹,

Kobayashi²,

Berthier³

et al. 2021

Rep. Prog. Phys.

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The pseudo-relativistic chiral electrons in 2D graphene and 3D topological semimetals, known as the massless Dirac or Weyl fermions, constitute various intriguing issues in modern condensed-matter physics. In particular, the issues linked to the Coulomb interaction between the chiral electrons attract great attentions due to their unusual features, namely, the interaction is not screened and has a long-ranged property near the charge-neutrality point, in clear contrast to its screened and short-ranged properties in the conventional correlated materials. In graphene, this long-range interaction induces an anomalous logarithmic renormalization of the Fermi velocity, which causes a nonlinear reshaping of its Dirac cone. In addition, for strong interactions, it even leads to the predictions of an excitonic condensation with a spontaneous mass generation. The interaction, however, would seem to be not that large in graphene, so that the latter phenomenon appears to have not yet been observed. Contrastingly, the interaction is probably large in the pressurized organic material α-(BEDT-TTF)2I3, where a 2D massless-Dirac-fermion phase emerges next to a correlated insulating phase. Therefore, an excellent testing ground would appear in this material for the studies of both the velocity renormalization and the mass generation, as well as for those of the short-range electronic correlations. In this review, we give an overview of the recent progress on the understanding of such interacting chiral electrons in 2D, by placing particular emphasis on the studies in graphene and α-(BEDT-TTF)2I3. In the first half, we briefly summarize our current experimental and theoretical knowledge about the interaction effects in graphene, then turn attentions to the understanding in α-(BEDT-TTF)2I3, and highlight its relevance to and difference from graphene. The second half of this review focusses on the studies linked to the nuclear magnetic resonance experiments and the associated model calculations in α-(BEDT-TTF)2I3. These studies allow us to discuss the anisotropic reshaping of a tilted Dirac cone together with various electronic correlations, and the precursor excitonic dynamics growing prior to a condensation. We see these provide unique opportunities to resolve the momentum dependence of the spin excitations and fluctuations that are strongly influenced by the long-range interaction near the Dirac points.

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Melting of Domain Wall in Charge Ordered Dirac Electron of Organic Conductor α-(BEDT-TTF)₂I₃

Cited by 7 publications

References 52 publications

Domain wall conductivity with strong Coulomb interaction of two-dimensional massive Dirac electrons in the organic conductor α−(BEDT−TTF)2I3

Domain wall conductivity with strong Coulomb interaction of two-dimensional massive Dirac electrons in the organic conductor α−(BEDT−TTF)2I3

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Interacting chiral electrons at the 2D Dirac points: a review

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Melting of Domain Wall in Charge Ordered Dirac Electron of Organic Conductor α-(BEDT-TTF)2I3

Cited by 7 publications

References 52 publications

Domain wall conductivity with strong Coulomb interaction of two-dimensional massive Dirac electrons in the organic conductor α−(BEDT−TTF)2I3

Domain wall conductivity with strong Coulomb interaction of two-dimensional massive Dirac electrons in the organic conductor α−(BEDT−TTF)2I3

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Interacting chiral electrons at the 2D Dirac points: a review

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Product

Resources

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Melting of Domain Wall in Charge Ordered Dirac Electron of Organic Conductor α-(BEDT-TTF)₂I₃