Metal-insulator transition in the dimerized organic conductor 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi><mml:mo>−</mml:mo><mml:mo>(</mml:mo><mml:mtext>BEDT-TTF</mml:mtext><mml:msub><mml:mo>)</mml:mo><mml:mn>2</mml:mn></mml:msub><mml:mi>Hg</mml:mi><mml:mo>(</mml:mo><mml:mi>SCN</mml:mi><mml:msub><mml:mo>)</mml:mo><mml:mn>2</mml:mn></mml:msub><mml:mi>Br</mml:mi></mml:math>

Ivek, Tomislav; Beyer, R.; Badalov, S. V.; Čulo, Matija; Tomić, Silvia; Schlueter, John A.; Zhilyaeva, E. I.; Lyubovskaya, Rimma N.; Dressel, Martin

doi:10.1103/physrevb.96.085116

Cited by 24 publications

(36 citation statements)

References 61 publications

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“…At temperatures between 150 and 100 K we observe a small change of a slope of the temperature dependence of the position of the ν 2 mode. This change occurs still in the metallic state (12). The change is close to the size of an error with which we determine parameters of the bands.…”

Section: Temperature Dependence Of Vibrational Modes For κ-Hg-brsupporting

confidence: 67%

“…A comparatively small width of the band, as well as its increase in intensity and its low-frequency shift below T =80 K distinguishes it from a Boson peak observed in glasses [27] and supports an interpretation in terms of a fluctuating system of dipoles versus charge glass. An absence of glassy behavior is also supported by the low frequency dielectric response of -Hg-Br [12].…”

mentioning

confidence: 76%

“…Here we elucidate the properties of the quantum dipole liquid state in the triangular lattice Mott insulator [9,10] -(BEDT-TTF) 2 Hg(SCN) 2 Br ( -Hg-Br ) (T = 80 K [11,12]) by comparing them to those of an isostructural compound -(BEDT-TTF) 2 Hg(SCN) 2 Cl ( -Hg-Cl), which shows signatures of a quantum dipole solid below 30 K [11,10]. We first use Raman molecular vibrational spectroscopy to follow the evolution of the distribution of charge on the lattice of these systems through the metal-insulator transition.…”

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confidence: 99%

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Evidence for a quantum dipole liquid state in an organic quasi–two-dimensional material

Hassan

Cunningham

Mourigal

et al. 2018

Science

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Mott insulators are commonly pictured with electrons localized on lattice sites, with their low-energy degrees of freedom involving spins only. Here, we observe emergent charge degrees of freedom in a molecule-based Mott insulator κ-(BEDT-TTF)Hg(SCN)Br, resulting in a quantum dipole liquid state. Electrons localized on molecular dimer lattice sites form electric dipoles that do not order at low temperatures and fluctuate with frequency detected experimentally in our Raman spectroscopy experiments. The heat capacity and Raman scattering response are consistent with a scenario in which the composite spin and electric dipole degrees of freedom remain fluctuating down to the lowest measured temperatures.

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Section: Temperature Dependence Of Vibrational Modes For κ-Hg-brsupporting

confidence: 67%

mentioning

confidence: 76%

mentioning

confidence: 99%

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Evidence for a quantum dipole liquid state in an organic quasi–two-dimensional material

Hassan

Cunningham

Mourigal

et al. 2018

Science

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“…Since the optical properties are rather isotropic within the highly-conducting plane, we focus on the polarization along the direction of the largest conductivity and present the data for the perpendicular axis in the Supplementary information S3. The most prominent feature is the Mott-Hubbard band centered around 2000 cm -1 , also seen in related materials [16,17,18,19]. Our CTQMC calculations reproduce the overall shape, asymmetry and intensity of the bands very well, establishing the dominant role of Mott physics in these compounds.…”

Section: Optical Studiessupporting

confidence: 61%

Quantum spin liquids unveil the genuine Mott state

et al. 2018

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The localization of charge carriers by electronic repulsion was suggested by Mott in the 1930s to explain the insulating state observed in supposedly metallic NiO. The Mott metal-insulator transition has been subject of intense investigations ever since-not least for its relation to high-temperature superconductivity. A detailed comparison to real materials, however, is lacking because the pristine Mott state is commonly obscured by antiferromagnetism and a complicated band structure. Here we study organic quantum spin liquids, prototype realizations of the single-band Hubbard model in the absence of magnetic order. Mapping the Hubbard bands by optical spectroscopy provides an absolute measure of the interaction strength and bandwidth-the crucial parameters that enter calculations. In this way, we advance beyond conventional temperature-pressure plots and quantitatively compose a generic phase diagram for all genuine Mott insulators based on the absolute strength of the electronic correlations. We also identify metallic quantum fluctuations as a precursor of the Mott insulator-metal transition, previously predicted but never observed. Our results suggest that all relevant phenomena in the phase diagram scale with the Coulomb repulsion U, which provides a direct link to unconventional superconductivity in cuprates and other strongly correlated materials.

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“…It appears in both polarizations at temperatures below the Mott transition [43] at 80 K (Figure 3a,b). This excitation is attributed [17] to a collective excitation of dipoles fluctuating on (BEDT-TTF) +1 2 dimers in the insulating state of κ-(BEDT-TTF) 2 Hg(SCN) 2 Br, forming "quantum dipole liquid".…”

Section: Mott Insulator On a Triangular Lattice: κ-(Bedt-ttf) 2 Cu 2 mentioning

confidence: 96%

Raman Scattering as a Probe of the Magnetic State of BEDT-TTF Based Mott Insulators

et al. 2018

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Quasi-two-dimensional Mott insulators based on BEDT-TTF molecules have recently demonstrated a variety of exotic states, which originate from electron-electron correlations and geometrical frustration of the lattice. Among those states are a triangular S = 1/2 spin liquid and quantum dipole liquid. In this article, we show the power of Raman scattering technique to characterize magnetic and electronic excitations of these states. Our results demonstrate a distinction between a spectrum of magnetic excitations in a simple Mott insulator with antiferromagnetic interactions, and a spectrum of an insulator with an additional on-site charge degree of freedom.

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Metal-insulator transition in the dimerized organic conductor κ−(BEDT-TTF)2Hg(SCN)2Br

Cited by 24 publications

References 61 publications

Evidence for a quantum dipole liquid state in an organic quasi–two-dimensional material

Evidence for a quantum dipole liquid state in an organic quasi–two-dimensional material

Quantum spin liquids unveil the genuine Mott state

Raman Scattering as a Probe of the Magnetic State of BEDT-TTF Based Mott Insulators

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