scholarly journals Tuning Charge Order in (TMTTF)2X by Partial Anion Substitution

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1545
Author(s):  
Andrej Pustogow ◽  
Daniel Dizdarevic ◽  
Sebastian Erfort ◽  
Olga Iakutkina ◽  
Valentino Merkl ◽  
...  
Keyword(s):  
Energy Gap ◽  
Charge Order ◽  
Coulomb Repulsion ◽  
Partial Substitution ◽  
Electronic Charge ◽  
Universal Relationship ◽  
Anions And Cations ◽  
Correlation Strength ◽  
Two Parameters ◽  
Ordered State

In the quasi-one-dimensional (TMTTF)2X compounds with effectively quarter-filled bands, electronic charge order is stabilized from the delicate interplay of Coulomb repulsion and electronic bandwidth. The correlation strength is commonly tuned by physical pressure or chemical substitution with stoichiometric ratios of anions and cations. Here, we investigate the charge-ordered state through partial substitution of the anions in (TMTTF)2[AsF6]1−x[SbF6]x with x≈0.3, determined from the intensity of infrared vibrations, which is sufficient to suppress the spin-Peierls state. Our dc transport experiments reveal a transition temperature TCO = 120 K and charge gap ΔCO=430 K between the values of the two parent compounds (TMTTF)2AsF6 and (TMTTF)2SbF6. Upon plotting the two parameters for different (TMTTF)2X, we find a universal relationship between TCO and ΔCO yielding that the energy gap vanishes for transition temperatures TCO≤60 K. While these quantities indicate that the macroscopic correlation strength is continuously tuned, our vibrational spectroscopy results probing the local charge disproportionation suggest that 2δ is modulated on a microscopic level.

PHASE TRANSITION IN TWO-DIMENSIONAL DILUTE ISING COULOMB GAS

1988 ◽  
Vol 02 (06) ◽  
pp. 1443-1445
Author(s):  
K. Y. SZETO
Keyword(s):  
High Temperature Superconductors ◽  
Magnetic Phase Diagram ◽  
Coulomb Repulsion ◽  
Logarithmic Potential ◽  
Real Space ◽  
Coulomb Gas ◽  
Two Dimensions ◽  
Electronic Charge ◽  
Spin Variable ◽  
Bare Interaction

The magnetic phase diagram of a dilute gas carrying an Ising spin variable and an electronic charge in two dimensions is investigated using a self consistent screening analysis. The bare interaction consists of a long range logarithmic potential which can be attractive (repulsive) for antiparallel (parallel) Ising spins and a screened Coulomb repulsion. The Ising Coulomb gas exhibits a real space pairing of antiparallel spins at low temperature and a plasma phase of free particles at high temperatures. The relevance of this model to pair formation in high temperature superconductors is discussed in the context of doped La 2 CuO 4.

Out-of-Plane Disorder Effects on the Energy Gaps and Electronic Charge Order in Bi2Sr1.7R0.3CuO6+δ (R = La and Eu)

2016 ◽  
Vol 85 (4) ◽  
pp. 044709 ◽  
Author(s):  
Tohru Kurosawa ◽  
Kohsaku Takeyama ◽  
Stefan Baar ◽  
Yuto Shibata ◽  
Moeko Kataoka ◽  
...  
Keyword(s):  
Charge Order ◽  
Electronic Charge ◽  
Disorder Effects ◽  
Energy Gaps ◽  
Out Of Plane

Optimal control strategies for coupled quantum dots

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
Esa Räsänen ◽  
Antti Putaja ◽  
Yousof Mardoukhi
Keyword(s):  
Optimal Control ◽  
Quantum Dots ◽  
Density Functional ◽  
Local Density ◽  
Control Strategies ◽  
Coulomb Repulsion ◽  
Laser Pulses ◽  
Electronic Charge ◽  
Coupled Quantum Dots ◽  
Functional Theory

AbstractSemiconductor quantum dots are ideal candidates for quantum information applications in solid-state technology. However, advanced theoretical and experimental tools are required to coherently control, for example, the electronic charge in these systems. Here we demonstrate how quantum optimal control theory provides a powerful way to manipulate the electronic structure of coupled quantum dots with an extremely high fidelity. As alternative control fields we apply both laser pulses as well as electric gates, respectively. We focus on double and triple quantum dots containing a single electron or two electrons interacting via Coulomb repulsion. In the two-electron situation we also briefly demonstrate the challenges of timedependent density-functional theory within the adiabatic local-density approximation to produce comparable results with the numerically exact approach.

scholarly journals Coulomb repulsion and correlation strength in LaFeAsO from density functional and dynamical mean-field theories

2009 ◽  
Vol 21 (7) ◽  
pp. 075602 ◽  
Author(s):  
V I Anisimov ◽  
Dm M Korotin ◽  
M A Korotin ◽  
A V Kozhevnikov ◽  
J Kuneš ◽  
...  
Keyword(s):  
Density Functional ◽  
Mean Field ◽  
Coulomb Repulsion ◽  
Field Theories ◽  
Correlation Strength ◽  
Mean Field Theories

scholarly journals Nature and evolution of incommensurate charge order in manganites visualized with cryogenic scanning transmission electron microscopy

2018 ◽  
Vol 115 (7) ◽  
pp. 1445-1450 ◽  
Author(s):  
Ismail El Baggari ◽  
Benjamin H. Savitzky ◽  
Alemayehu S. Admasu ◽  
Jaewook Kim ◽  
Sang-Wook Cheong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Room Temperature ◽  
Charge Order ◽  
Transmission Electron ◽  
Phase Inhomogeneity ◽  
Scanning Transmission ◽  
Lattice Coupling ◽  
Ordered State

Incommensurate charge order in hole-doped oxides is intertwined with exotic phenomena such as colossal magnetoresistance, high-temperature superconductivity, and electronic nematicity. Here, we map, at atomic resolution, the nature of incommensurate charge–lattice order in a manganite using scanning transmission electron microscopy at room temperature and cryogenic temperature (∼93 K). In diffraction, the ordering wave vector changes upon cooling, a behavior typically associated with incommensurate order. However, using real space measurements, we discover that the ordered state forms lattice-locked regions over a few wavelengths interspersed with phase defects and changing periodicity. The cations undergo picometer-scale (∼6 pm to 11 pm) transverse displacements, suggesting that charge–lattice coupling is strong. We further unearth phase inhomogeneity in the periodic lattice displacements at room temperature, and emergent phase coherence at 93 K. Such local phase variations govern the long-range correlations of the charge-ordered state and locally change the periodicity of the modulations, resulting in wave vector shifts in reciprocal space. These atomically resolved observations underscore the importance of lattice coupling and phase inhomogeneity, and provide a microscopic explanation for putative “incommensurate” order in hole-doped oxides.

scholarly journals Density-functional calculation of the Coulomb repulsion and correlation strength in superconducting LaFeAsO

JETP Letters ◽  
2008 ◽  
Vol 88 (11) ◽  
pp. 729-733 ◽  
Author(s):  
V. I. Anisimov ◽  
Dm. M. Korotin ◽  
S. V. Streltsov ◽  
A. V. Kozhevnikov ◽  
J. Kuneš ◽  
...  
Keyword(s):  
Density Functional ◽  
Coulomb Repulsion ◽  
Density Functional Calculation ◽  
Correlation Strength

scholarly journals Terahertz-field-induced polar charge order in electronic-type dielectrics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
H. Yamakawa ◽  
T. Miyamoto ◽  
T. Morimoto ◽  
N. Takamura ◽  
S. Liang ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Quantum Physics ◽  
Second Harmonic ◽  
Charge Order ◽  
Spin Liquid ◽  
Molecular Compound ◽  
Electronic Phase ◽  
Spin Liquid State ◽  
Order State ◽  
Ordered State

AbstractUltrafast electronic-phase change in solids by light, called photoinduced phase transition, is a central issue in the field of non-equilibrium quantum physics, which has been developed very recently. In most of those phenomena, charge or spin orders in an original phase are melted by photocarrier generations, while an ordered state is usually difficult to be created from a non-ordered state by a photoexcitation. Here, we demonstrate that a strong terahertz electric-field pulse changes a Mott insulator of an organic molecular compound in κ-(ET)2Cu[N(CN)2]Cl (ET = bis(ethylenedithio)tetrathiafulvalene), to a macroscopically polarized charge-order state; herein, electronic ferroelectricity is induced by the collective intermolecular charge transfers in each dimer. In contrast, in an isostructural compound, κ-(ET)2Cu2(CN)3, which shows the spin-liquid state at low temperatures, a similar polar charge order is not stabilized by the same terahertz pulse. From the comparative studies of terahertz-field-induced second-harmonic-generation and reflectivity changes in the two compounds, we suggest the possibility that a coupling of charge and spin degrees of freedom would play important roles in the stabilization of polar charge order.

Co-existence of charge order and spin Peierls lattice distortion in one-dimensional organic compounds

2002 ◽  
Vol 12 (9) ◽  
pp. 205-209
Author(s):  
H. Seo ◽  
M. Kuwabara ◽  
M. Ogata
Keyword(s):  
Ground State ◽  
Lattice Distortion ◽  
Charge Order ◽  
Combined Effects ◽  
Strongly Correlated ◽  
Coulomb Interactions ◽  
Phonon Interaction ◽  
One Dimensional ◽  
Electron Phonon Interaction ◽  
Ordered State

The ground state properties of the organic spin-Peierls compounds with one-dimensional quarter-filled band are investigated theoretically. In the strongly correlated regime, two insulating states compete to each other, which are the charge ordered state due to the inter-site Coulomb interaction, and the `dimer Mott' insulating state due to the combined effects of the electron-phonon and the on-site Coulomb interactions. In both of these states, the electron-phonon interaction further produces the lattice tetramization, which is interpreted as the spin-Peierls state.

ADSORPTION OF H2 AND O2 GASES ON ZnO WURTZOID NANOCRYSTALS: A DFT STUDY

2017 ◽  
Vol 24 (Supp01) ◽  
pp. 1850008 ◽  
Author(s):  
MUDAR AHMED ABDULSATTAR ◽  
HASAN MUDAR ALMAROOF
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Main Reaction ◽  
Electronic Charge ◽  
Zno Nanostructures ◽  
Functional Theory ◽  
Zno Nanocrystals ◽  
Adsorbed Atoms ◽  
Zno Nanocrystal

In the present work, we apply wurtzoids nanocrystals with density functional theory to explain the sensitivity of ZnO nanostructures towards hydrogen and oxygen molecules. Present results of ZnO nanocrystals’ sensing to H2 and O2 molecules show a reduction in the energy gap and hence electrical resistivity of ZnO nanocrystals upon attachments of these molecules in agreement with experiment. The results also show that higher temperatures increase the sensitivity of ZnO wurtzoids towards H2 and O2 molecules with the maximum sensitivity approximately at 390[Formula: see text]C and 417[Formula: see text]C for H2 and O2 molecules, respectively, after which it begins to decline according to calculated Gibbs free energy. These temperatures are comparable with experimentally reported operating temperatures of 325[Formula: see text]C and 350[Formula: see text]C for the two gases, respectively. The main reaction mechanism is the dissociation of H2 or O2 molecules on ZnO nanocrystal surface in which hydrogen and oxygen atoms are attached to neighboring Zn and O surface atoms. The removal of these molecules from the surface is also performed by the formation of H2 and O2 molecules prior to their removal from the ZnO nanocrystal surface. Electronic charge transfers to the adsorbed atoms and molecules confirm and illustrate the mechanism mentioned above.

Electrical conductivity and density of state of boron nitride nanotubes due to electronic correlation

2014 ◽  
Vol 28 (26) ◽  
pp. 1450180 ◽  
Author(s):  
H. Rezania
Keyword(s):  
Electrical Conductivity ◽  
Boron Nitride ◽  
Energy Gap ◽  
Coulomb Repulsion ◽  
Boron Nitride Nanotubes ◽  
Electron Interaction ◽  
Electronic Correlation ◽  
Density Of State ◽  
Gw Approximation ◽  
Function Matrix

The temperature behavior of electrical conductivity of boron nitride nanotubes (6, 0) in the context of Hubbard model at the paramagnetic sector. The effect of electronic correlation on the energy gap of boron nitride nanotube (BNNT) is investigated. Interacting electronic Green's function matrix has been found within GW approximation. Using Kubo formula, electrical conductivity of the system has been calculated. The results show that the band gap in the density of state decreases with Coulomb repulsion strength. Moreover, the increase of electronic correlation leads to decrease electrical conductivity of BNNT. Also the electrical conductivity shows an exponential behavior in terms of temperature at all the values of electron–electron interaction parameter.

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