Showing papers on "Mott transition published in 1996"
TL;DR: In this article, the phase diagram and critical properties of both Mott transitions at fixed filling and upon doping, as well as the dc and ac conductivity are discussed. And application of these results to organic conductors is discussed.
Abstract: I review some of the results on the Mott transition in one dimensional systems. In particular I discuss the phase diagram and critical properties of both Mott transitions at fixed filling and upon doping, as well as the dc and ac conductivity. Application of these results to organic conductors is discussed.
113 citations
IBM1
TL;DR: In this article, the Mott transition field effect transistor (MTFET) was proposed and analyzed for a class of organic charge transfer complexes, and its performance was shown to be feasible down to nanoscale dimensions.
Abstract: Here we propose and analyze the behavior of a FET--like switching device, the Mott transition field effect transistor, operating on a novel principle, the Mott metal--insulator transition. The device has FET-like characteristics with a low ``ON'' impedance and high ``OFF'' impedance. Function of the device is feasible down to nanoscale dimensions. Implementation with a class of organic charge transfer complexes is proposed.
86 citations
TL;DR: In this article, a variational Monte Carlo calculation is performed to locate the instability of the "metallic" wave function with respect to antiferromagnetic instability and the Mott phenomenon.
Abstract: The Hubbard model is investigated for a halffilled honeycomb lattice, using a variational method. Two trial wave functions are introduced, the Gutzwiller wave function, well suited for describing the “metallic” phase at small U and a complementary wave function for the insulating regime at large values of U. The comparison of the two variational ground states at the mean-field level yields a Mott transition at U
c
/t ≈ 5:3. In addition, a variational Monte Carlo calculation is performed in order to locate the instability of the “metallic” wave function with respect to antiferromagnetism. The critical value U
m/t ≈ 3:7 obtained in this way is considered to be a lower bound for the true critical point for antiferromagnetism, whereas there are good arguments that the mean-field value U
c/t ≈ 5:3 represents an upper bound for the Mott transition. Therefore the “metal”- insulator transition for the honeycomb lattice may indeed be simultaneously driven by the antiferromagnetic instability and the Mott phenomenon.
48 citations
TL;DR: The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition as discussed by the authors.
Abstract: The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition The zero-temperature (T) transition was tuned with pressure, and significant deviations were found near the quantum critical point from the usual T1/2 behavior of the conductivity characteristic of electron-electron interactions in the presence of disorder The transport data for pressure and temperature below 1 kelvin could be collapsed onto a universal scaling curve
47 citations
TL;DR: The Mott transition phenomena can be studied systematically in the limit of large lattice spatial coordination and the properties of doped Mott insulators with a variety of techniques are investigated.
Abstract: The Mott transition phenomena can be studied systematically in the limit of large lattice spatial coordination. We investigate the properties of doped Mott insulators with a variety of techniques and compare our results with experiments on transition-metal oxides. \textcopyright{} 1996 The American Physical Society.
44 citations
TL;DR: In this paper, the authors studied the metal-insulator transitions of La 3 Ni 2 O 7-δ and La 4 Ni 3 O 10−δ with layered structure and revealed an existence of the sharp transition in both systems at 550 K from a metallic but less conducting state with localized spins at Ni sites to the Pauli paramagnetic and more conducting one with increasing temperature.
Abstract: Metal-insulator transitions of La 3 Ni 2 O 7-δ and La 4 Ni 3 O 10-δ with layered structure have been studied. Transport and magnetic measurements up to 1000 K have revealed an existence of the sharp transition in both systems at 550 K from a metallic but less conducting state with localized spins at Ni sites to the Pauli paramagnetic and more conducting one with increasing temperature. The transition is explained by a model that the Mott transition takes place in the “half-filled” band of 3 d 3 z 2 - r 2 orbitals at the temperature, and that below the temperature, the conduction of the electrons in the 3 d x 2 - y 2 band is disturbed by the Hund coupling with the localized electrons in the 3 d 3 z 2 - r 2 band.
42 citations
TL;DR: It is shown that the quantitative aspects of the low-energy behavior near the Mott insulating state with one electron per site are not very sensitive to orbital degeneracy, justifying the quantitative success of the one-band model which had been previously applied to orbitally degenerate systems.
Abstract: We investigate the Mott transition in infinite dimensions in the orbitally degenerate Hubbard model The qualitative features of the Mott transition found in the one-band model are also present in the orbitally degenerate case We show that the quantitative aspects of the low-energy behavior near the Mott insulating state with one electron per site are not very sensitive to orbital degeneracy, justifying the quantitative success of the one-band model which had been previously applied to orbitally degenerate systems We contrast this with quantities that have a sizable dependence on the orbital degeneracy and comment on the role of the intra-atomic exchange {ital J} {copyright} {ital 1996 The American Physical Society}
36 citations
TL;DR: In this article, critical properties associated with Mott transitions are investigated in the finite temperature SUf(3) Nambu-Jona-Lasinio model, that describes quarks u, d, s and bound mesons π, K.
35 citations
TL;DR: In this article, the spin and charge phase diagram of a three-legs ladder is studied as a function of fermion density and of transverse single-particle hopping.
28 citations
TL;DR: The Mott metal-insulator transition induced by an external electric field is discussed based on an analysis of a double-layered two-dimensional lattice model that is applicable to a Mott transition in a two- dimensional array of very small quantum dots whose shape is asymmetric in the direction perpendicular to the substrate.
Abstract: The Mott metal-insulator transition induced by an external electric field is discussed based on an analysis of a double-layered two-dimensional lattice model. A sharp transition between a metallic phase with the antiferromagnetic order and a Mott insulating phase is found to be driven by the voltage difference between the two layers. A sharp metal-insulator transition is transformed to a smooth metal-insulator transition by a change in the coupling between sites This model is applicable to a Mott transition in a two-dimensional array of very small quantum dots whose shape is asymmetric in the direction perpendicular to the substrate. \textcopyright{} 1996 The American Physical Society.
22 citations
TL;DR: In this paper, the single-particle spectral functions for the two-dimensional t -J model are investigated in connection with spin and charge dynamics, using the exact diagonalization technique.
Abstract: The single-particle spectral functions for the two-dimensional t - J model are investigated in connection with spin and charge dynamics, using the exact diagonalization technique. At low electron density, Fermi liquid behavior is observed. Near half-filling, the spectral functions reveal a two-peak structure which is due to the different dynamics of spin and charge degrees of freedom. This density dependence of the spectral functions indicates a crossover from Fermi liquid behavior at low density to anomalous behavior near the Mott transition where the approximate decoupling of spin and charge excitations occurs.
TL;DR: In this article, the Mott transition in infinite dimensions in the orbitally degenerate Hubbard model was investigated and it was shown that the qualitative and quantitative aspects of the transition around density one are not very sensitive to orbital degeneracy, justifying the quantitative success of the one band model.
Abstract: We investigate the Mott transition in infinite dimensions in the orbitally degenerate Hubbard model. We find that the qualitative features of the Mott transition found in the one band model are also present in the orbitally degenerate case. Surprisingly, the quantitative aspects of the transition around density one are not very sensitive to orbital degeneracy, justifying the quantitative success of the one band model which was previously applied to orbitally degenerate systems. We contrast this with quantities that have a sizeable dependence on the orbital degeneracy and comment on the role of the intraatomic exchange J.
TL;DR: In this paper, the authors investigated magnetic susceptibility, magnetization and ESR in order to clarify the correlation between the magnetism and the electronic structure of BEDT-TTF.
Abstract: (BEDT-TTF) 3 CuBr 4 is a two-dimensional organic conductor whose structure consists of alternate stacking of BEDT-TTF π conducting sheets and magnetic Cu 2+ sheets. We investigate magnetic susceptibility, magnetization and ESR in order to clarify the correlation between the magnetism and the electronic structure. Above a structural transition T c =59 K, the magnetic susceptibility indicates the presence of strong antiferromagnetic interaction between the π-electrons on BEDT-TTF and the localized d -electrons on Cu 2+ . The transition brings about the disappearance of the magnetic moments of BEDT-TTF molecules below T c , which indicates the change from a Mott insulator to a band insulator state. Below T c , the susceptibility is governed only by Cu 2+ spins, and shows an antiferromagnetic transition at T N =7.65 K, where the π-electrons play an important role in the exchange interactions.
TL;DR: The one-dimensional (1D) $t$-$J$ model is investigated by using a Gutzwiller-Jastrow-type variation method and the exact diagonalization of small systems, which shows some behaviors which are not expected in repulsive models, as the value of $J/t$ increases.
Abstract: The one-dimensional (1D) t-J model is investigated by using a Gutzwiller-Jastrow-type variation method and the exact diagonalization of small systems. Variational expectation values are estimated by the variational Monte Carlo method with sufficient accuracy. First, we give detailed descriptions of the preceding paper [Phys. Rev. Lett. 67, 3610 (1991)], where we discussed the properties of the Fermi-liquid-type Jastrow wave function as well as the Gutzwiller wave function. Secondly, these wave functions are compared with the Tomonaga-Luttinger-liquid-type wave function proposed by Hellberg and Mele. It is found that the correlation factors in short distances control bulk quantities like energy and the magnitude of the correlation functions, while the long-range part of the correlation factors determines the critical behavior of correlation functions. Finally, using these functions, charge, spin susceptibilities, and magnetization curve are estimated, which agree with the exact results. It is shown that the Mott transition in the 1D t-J model is quite different from the Brinkman-Rice transition. \textcopyright{} 1996 The American Physical Society.
TL;DR: In this article, the authors studied the doped Mott insulator in one dimension based on the phase Hamiltonian with the Umklapp scattering process, in which the charge degree of freedom is described by the quantum sine-Gordon model.
Abstract: The doped Mott insulator in one dimension has been studied based on the phase Hamiltonian with the Umklapp scattering process, in which the charge degree of freedom is described by the quantum sine-Gordon model. The well-known equivalence between the quantum sine-Gordon model and the massive Thirring model for the spinless fermion makes it clear that the Mott-Hubbard gap originates from the Umklapp scattering process as was indicated by Emery and Giamarchi. Compressibility, density-density correlation function, frequency dependence of optical conductivity and Drude weight have been calculated in the presence of the impurity scattering treated in the self-consistent Born approximation. It is seen that there exists a crossover behavior in the spectral weight of charge excitations: the acoustic mode is dominant in small wave number region while the optical excitations across the Mott-Hubbard gap lie in large wave number region and that this crossover wave number is reduced as the Mott transition is approached.
TL;DR: The competition between the Mott transition and the Anderson localization in one-dimensional electron systems is studied with the bosonization and renormalization-group methods and it is found that sufficiently strong forward scattering by random impurities destroys theMott-Hubbard gap, and backward scattering gives rise to Anderson localization for the resulting gapless state.
Abstract: The competition between the Mott transition and the Anderson localization in one-dimensional electron systems is studied with the bosonization and renormalization-group methods. The $\ensuremath{\beta}$ function is calculated up to second order in the strength of diagonal disorder by using a replica trick. It is found that sufficiently strong forward scattering by random impurities destroys the Mott-Hubbard gap, and backward scattering gives rise to Anderson localization for the resulting gapless state. On the other hand, if the umklapp interaction is strong enough, the Mott insulating state still overwhelms the Anderson localization.
TL;DR: In this article, the physical properties of the strongly correlated electron system La 1.17-x Sr x VS 3.17 have been investigated and it has been shown that the electronic specific heat coefficient γ seems not to be enhanced as the system approaches the metal-insulator phase boundary from the metallic side.
Abstract: Experimental studies on physical properties of the two dimensional strongly correlated electron system La 1.17- x Sr x VS 3.17 have been carried out. In the x region around 0.17, where the V-valency is ∼+3, the system is considered to be in a Mott insulating phase. With increasing x up to the region \(\gtrsim0.3\), it becomes essentially metallic. Measurements of the thermal dilatation and the ultrasonic velocity have presented experimental evidence that a certain type of lattice distortion is involved in the phase transition observed previously by magnetic studies for samples with x ∼0.17. The electronic specific heat coefficient γ seems not to be enhanced as the system approaches the metal-insulator phase boundary from the metallic side.
TL;DR: In this article, the transport, magnetic and thermal properties of La 1.17 − x Sr x VS 3.17 have been studied and it has been shown that the anomalous behavior of R H and S observed in the carrier-doped phase is very similar to that of high-T c oxides, indicating that the existence of these anomalous behaviors is common to 2D Mott systems.
Abstract: Transport, magnetic and thermal properties of La 1.17 − x Sr x VS 3.17 have been studied. The compound is pointed out to be in the Mott insulating state around x = 0.17, where localized spins undergo a transition caused by the singlet formation with the aid of a certain type of lattice distortion. Both electron-type ( x x > 0.17) carriers can be doped into the Mott insulating phase, and an essentially metallic state is realized for x ≳ 0.30. The anomalous behavior of R H and S observed in the carrier-doped phase is very similar to that of high- T c oxides, indicating that the existence of these anomalous behaviors is common to 2D Mott systems. The electronic specific heat coefficient γ decreases as the system approaches the metal-insulator phase boundary, which also seems to be similar to the case of high- T c oxides.
TL;DR: In this paper, the Mott transition was found to be sensitive to pressure over a very wide temperature region and the paramagnetic insulator state, which exists in the region of \(x\lesssim 0.15\) above the Neel temperature, exhibits a transition to a metallic state at a rather small value of applied pressure p.
Abstract: Electrical resistivities ρ of BaCo 1- x Ni x S 2 , which has a layered structure and exhibits the Mott transition with varying x , have been found to be strongly sensitive to pressure over a very wide temperature region. The paramagnetic insulator state, which exists in the region of \(x\lesssim0.15\) above the Neel temperature T N , exhibits a transition to a metallic state at a rather small value of applied pressure p . The temperature T N , at which the resistivity ρ exhibits anomalous increase with decreasing T , rapidly decreases with increasing p and becomes zero at the critical value of p = p c ( x ) (\(\lesssim15\,\)kbar for x ≥0.05). The paramagnetic state thus obtained exhibits roughly T 2 -like dependence of the resistivity. The metal-insulator transition of the present system is known to be easily controlled by the external pressure.
TL;DR: In this paper, the transport properties of V 4 -cluster compounds were discussed in terms of hopping of carriers in a Mott insulator in the presence of disorder, and the increased Zn-substitution of Ga gave homogeneous phases of F 4 3m symmetry and strong reduction in room temperature activation energy in conductivity from 0.14 to 0.04eV.
TL;DR: In this article, the weak coupling phase diagram of a system of three coupled spin 1/2 chains is studied as a function of fermion density and of transverse single-particle hopping by means of a renormalization group analysis.
Abstract: The weak-coupling phase diagram of a system of three coupled spin 1/2 chains (at zero temperature) is studied as a function of fermion density and of transverse single-particle hopping by means of a renormalization-group analysis. We identify different phases with a different behavior of the renormalization-group flow and interpret the effect of relevant couplings in terms of the associated bosonized Hamiltonian. A frustrated (gapped) magnetic spectrum in a large region about and at half filling is obtained in the unphysical case of periodic boundary conditions in the direction transverse to the chains. The expected spin phase diagram (as also observed in the Sr 2 Cu 3 O 5 ladder compounds) is instead obtained when open transverse boundary conditions are considered. In particular, the spin modes are ungapped in a wide region about half filling and at half filling down to a critical value of the transverse hopping t⊥. A Mott transition as a function of t⊥ is thus present at half filling.
TL;DR: In this article, the charge response of strongly correlated metals near the Mott transition is studied in comparison with Raman scattering experiments which show non-Fermi-liquid or marginal Fermi liquid behaviors.
Abstract: On the basis of the itinerant-localized duality model the charge response of strongly correlated metals near the Mott transition is studied in comparison with Raman scattering experiments which show non-Fermi-liquid or marginal-Fermi-liquid behaviors. Such behaviors are due to incoherent contribution which is neglected in the ordinary Fermi-liquid theory.
TL;DR: In this article, an addition spectral analysis on a finite cluster from the double-layered lattice model, which has been introduced to describe quantum dot arrays under an external electric field perpendicular to the array, is presented.
Abstract: An addition spectral analysis on a finite cluster from the double-layered lattice model, which has been introduced to describe quantum dot arrays under an external electric field perpendicular to the array, is presented. When the density of electrons is near to quarter-filled, we found a new type of Mott transition, in which the metal-insulator transition goes through a heavy-electron phase. In this new Mott transition, the Mott insulating state becomes unstable because Gibbs states having more pairs of electrons are favored as well as the Mott insulating state, resulting in an enhancement of electron-density fluctuation.
TL;DR: In this paper, the results of photoemission and inverse-photoemission studies of strongly correlated metallic systems which have one-, two-and three-dimensional crystal structures are presented. And the spectral weight distribution exhibits characteristic evolution as a function of band width and band filling as well as of mass anisotropy.
TL;DR: In this article, the authors investigated the Mott transition in the solid solution of 1T-TaSxSe2−x by scanning tunneling microscopy/spectroscopy (STM/STS) at 77 K.
Abstract: Mott transition in the solid solution of 1T-TaSxSe2−x was investigated by the scanning tunneling microscopy/spectroscopy (STM/STS) at 77 K. For x>1.5, a clear Mott-Hubbard gap structure of ∼0.5 eV, accompanied with two conductance peaks was observed. In TaS1.2Se0.8, on the other hand, it was found that the gap structure was collapsed. The x dependence of the tunneling spectrum is consistent with the Mott transition picture where the density of states near the Fermi level goes to zero with increasing x.
TL;DR: In this paper, the divergence in the electronic self-energy in an electron-phonon system with the on-site Coulomb repulsion was investigated, and the localization due to U and/or the phonon-mediated attractive interaction was studied.
Abstract: By investigating the divergence in the electronic self-energy in an electron-phonon system with the on-site Coulomb repulsionU, we study the localization due toU and/or the phonon-mediated attractive interactionV. In addition to the generalization of the Mott transition in the Hubbard model by includingV, particular attention is paid to the localization due to the confinement by local phonons occurring at finite energies which may be called as the dynamical localization.
TL;DR: In this article, the electrical resistivity of metallic V 2 y O 3 is calculated assuming that the antiferromagnetic spin fluctuations dominate the scattering mechanism for the conduction electrons, and the spin fluuations are described in terms of the self-consistent renormalization theory with parameter values estimated from the results of a neutron inelastic scattering experiment.
Abstract: The electrical resistivity of metallic V 2- y O 3 is calculated assuming that the antiferromagnetic spin fluctuations dominate the scattering mechanism for the conduction electrons. The spin flu- ctuations are described in terms of the self-consistent renormalization theory with parameter values estimated from the results of a neutron inelastic scattering experiment. The final result agrees reasonably well with the experimental results.
TL;DR: In this article, it was shown that in a correlated system, if a localized hole on a site creates a potential strong enough to extract a bound state from below the band, then the hole is self-trapped.
TL;DR: In this article, a model of the one-dimensional Coulomb-interacting few-particle system is studied in detail, where correlated wave functions for the system can be obtained from the Slater determinants constructed for the sets of one-electron levels and combined according to the rules given by the standard perturbation theory.
Abstract: A model of the one-dimensional Coulomb-interacting few-particle system is studied in detail. The model is similar to a many-electron system which in a zero-order approximation of the non-interacting particles has only singly occupied one-electron levels. Such model cancels the divergencies in the Coulomb and exchange interaction energies found regularly for a conventional one-dimensional system which is built up of the doubly occupied one-electron levels and is submitted to the Coulomb perturbation. In the present case, the correlated wave functions for the system can be obtained from the Slater determinants constructed for the sets of the one-electron levels and combined according to the rules given by the standard perturbation theory. The calculations allow us to discuss the correlation influence and the effect of the size of the model on: (i) the excitation energies including the criterion corresponding to the metal-insulator transition (the Mott transition), (ii) the distribution of the correlated charge along the model, (iii) the average velocity of a two-particle system being in different states, and (iv) the dipole moments and transition probabilities. In the last case, the lifetime of the uncorrelated and correlated excited states obtained in the situation of the allowed one-photon transitions can be compared with the lifetime obtained for a similar system in the case when the one-photon transitions are forbidden and two-photon transitions should be taken into account. No data other than the length of the model and the fundamental constants of nature enter the calculations.
TL;DR: In this paper, the metal-insulator transition in a generalized Hubbard model with bondcharge interaction has been studied by means of the auxiliary field technique, and the phase diagram in the parameter space spanned by the effective kinetic energy and the effective bond-charge interaction is presented for the three-dimensional case.
Abstract: The metal-insulator transition in a generalized Hubbard model with bondcharge interaction has been studied by means of the auxiliary field technique. The system exhibits both the conventional Mott-Hubbard transition, characterized by a continuous change in the number of current carriers, and a novel first-order metal-insulator transition owing to the bond-charge interaction, at which there is a discontinuity in the number of current carriers. The phase diagram in the parameter space spanned by the effective kinetic energy and the effective bond-charge interaction is presented for the three-dimensional case.