Showing papers on "Mott transition published in 1995"
Book•
01 Sep 1995
TL;DR: A survey of the fundamental problem related to the metallic and non-metallic states of matter can be found in this article, where the authors pose questions and challenges in this area, as well as highlight present understandings of the topic.
Abstract: This text surveys the various aspects of the fundamental problem related to the metallic and non-metallic states of matter, a question physicists have been studying for almost 100 years. The book poses questions and challenges in this area, as well as highlighting present understandings of the topic. Topics covered by the book include physics of dense ionized metal plasmas; metallic hydrogen; pressure-induced metallization; the M-I transition in doped semiconductors; transport studies in doped semiconductors near the metal-insulator transition; new results in old oxides; metal-insulator transition in 3d transition metal perovskite oxides investigated by high-energy spectroscopies; alkali metal-alkali halide melts; hopping conductivity in granular metals revisited; superconductor-insulator transition in cuprates; molecular metals and superconductors; shear induced chemical reactivity; shear, co-ordination and metallization; quantum diffusion and decoherence; the Mott transition; recent results, more and surprises; Mott-Hubbard-Anderson models.
103 citations
TL;DR: In this paper, the pressure-temperature phase diagram of the Mott transition model was calculated for the phase transition in Ce. The theory correctly describes the linear variation of the transition temperature with pressure and the existence of a critical point.
Abstract: We have calculated the pressure-temperature phase diagram of the $\ensuremath{\gamma}\ensuremath{\rightleftharpoons}\ensuremath{\alpha}$ isostructural transition in Ce on the basis of the Mott transition model. The theory correctly describes the linear variation of the transition temperature with pressure and the existence of a critical point. The quantitative agreement with the experimental diagram is good. The influence of different free energy contributions (configurational, magnetic, and vibrational) on the phase transition in Ce is discussed.
94 citations
TL;DR: The result implies that the effect of long-range Coulomb interaction as well as short-range interaction becomes increasingly important towards the transition, implying that the bandwidth remains finite as the system approaches the Mott transition.
Abstract: We have studied metallic ${\mathrm{SrVO}}_{3}$ and ${\mathrm{CaVO}}_{3}$ by inverse photoemission and high-resolution photoemission. In going from Sr to Ca, considerable spectral weight is transferred from the coherent band to the upper and lower Hubbard bands. Meanwhile, the overall intensity rather than the width of the coherent band decreases, implying that the bandwidth remains finite as the system approaches the Mott transition. The result implies that the effect of long-range Coulomb interaction as well as short-range interaction becomes increasingly important towards the transition.
93 citations
TL;DR: The low-energy scaling functions of the metallic state, including the single-particle Green function and dynamical spin susceptibility, as well as thermodynamic properties are determined.
Abstract: We introduce a systematic approach to analyze the low-energy behavior of strongly correlated electron systems in infinite dimensions, and apply it to the metal-insulator transition in the half-filled Hubbard model. We determine the low-energy scaling functions of the metallic state, including the single-particle Green function and dynamical spin susceptibility, as well as thermodynamic properties. Comparisons are made with experimental data on transition metal oxides.
92 citations
59 citations
TL;DR: In this paper, the influence of correlations on the critical temperature and density for the onset of superfluidity in nuclear matter is investigated within the scheme of Nozieres and Schmitt-Rink.
Abstract: The influence of correlations on the critical temperature and density for the onset of superfluidity in nuclear matter is investigated within the scheme of Nozieres and Schmitt-Rink [1]. For symmetric nuclear matter a smooth transition from Bose-Einstein condensation (BEC) of deuteronlike bound states at low densities and low temperatures to Bardeen-Cooper-Schrieffer (BCS) pairing at higher densities is described. Compared with the mean field approach a lowering of the critical temperature is obtained for symmetric nuclear matter as well as for pure neutron matter. The Mott transition in symmetric nuclear matter is discussed. Regions in the temperature-density plane are identified where correlated pairs give the main contribution to the composition of the system, so that approximations beyond the quasi-particle picture are requested.
55 citations
TL;DR: In this article, the scaling theory of the Mott insulator and metals in clean systems is analyzed in terms of quantum critical phenomena, and a new universality class with the correlation length exponent ν 2 is derived.
Abstract: Transitions between the Mott insulator and metals in clean systems are analyzed with the scaling theory in terms of quantum critical phenomena. In the case of generic transitions controlled by the filling, the scaling theory is established from analyses of the Drude weight and the compressibility based on hyperscaling. In the transition to the Mott insulator, a new universality class with the correlation length exponent ν 2 is derived, which is in contrast to the transition to the band insulator characterized by ν=1/2 and z =2. The unusual exponents lead to various anomalous characters of metals near the Mott insulator such as strong suppression of the degeneracy temperature, and nonlinear dependence of the Drude weight on the doping concentration. Remarkable properties are also found in the specific heat, the compressibility and spin correlations. A mechanism of high temperature superconductivity is discussed in terms of the release from the suppressed coherence.
48 citations
32 citations
TL;DR: It is shown that hysteresis can occur in the transition between a neutral plasma and the insulating gas consisting of neutral pairs bound by Coulomb attraction, and numerical results indicate where regions of bistability occur in density--temperature phase space.
Abstract: We show that hysteresis can occur in the transition between a neutral plasma and the insulating gas consisting of neutral pairs bound by Coulomb attraction. Since the transition depends sensitively on the screening length in the plasma, regions of bistability occur in density-temperature phase space. We present numerical results which indicate where these regions occur for systems such as spin-polarized hydrogen, positronium gas, and excitons in a semiconductor. (c) 1995 The American Physical Society
30 citations
TL;DR: In this article, anomalous properties of quasi-two-dimensional electrons of BaCo 1- x Ni x S 2 which exhibit the Mott metal-insulator transition are reported.
Abstract: Physical properties of quasi two-dimensional electrons of BaCo 1- x Ni x S 2 which exhibits the Mott metal-insulator transition are reported. Various anomalous behaviors which are similar to those of high- T c Cu oxides have been found. It is suggested that these anomalies are induced in the metallic and magnetically correlated state without long range order and therefore with very strong low energy magnetic fluctuations. It remains unclear if the system exhibits a decreasing tendency of the electronic specific heat coefficient γ upon approaching the Mott insulating phase, which is one of the remarkable anomalous behaviors of high- T c oxides. Superconductivity has not been found down to 1.4 K.
21 citations
TL;DR: In this article, the spin and charge phase diagram of a three-legs ladder at zero temperature is studied as a function of fermion density and of transverse single-particle hopping.
Abstract: We study the spin and charge phase diagram of a three-legs ladder (at zero temperature) as a function of fermion density and of transverse single-particle hopping by means of a Renormalization-Group analysis rigorously controlled in the weak-coupling limit. Periodic boundary conditions in the direction transverse to the ladder produce frustrated magnetic excitations yielding a spin-gapped phase in a large region about and at half filling. Spin correlations are instead enhanced when open transverse boundary conditions are considered, yielding an ungapped phase in a wide region about half filling (as observed in the Sr$_{n-1}$Cu$_{n+1}$O$_{2n}$ stripes compounds) and at half filling down to a critical value of the transverse hopping $t_{\perp}$. At that critical value, the system undergoes a Mott transition at half filling by decreasing $t_{\perp}$.
TL;DR: The exactly soluble 1/[ital r] Hubbard chain is studied at half filling and an iterative scheme is found to converge rapidly towards the exact results both for the ground-state energy and the double occupancy.
Abstract: The exactly soluble 1/[ital r] Hubbard chain is studied at half filling Two classes of variational wave functions are introduced, one representing the metallic phase, the other the insulating phase An iterative scheme is found to converge rapidly towards the exact results both for the ground-state energy and the double occupancy The insulating and metallic phases are connected by a duality relation, which allows one to locate exactly the critical value of the Hubbard parameter [ital U]
TL;DR: The Anderson-Mott transition of disordered interacting electrons is shown to share many physical and technical features with classical random-field systems, and random- field terms appear at one-loop order in this model.
Abstract: The Anderson-Mott transition of disordered interacting electrons is shown to share many physical and technical features with classical random-field systems. A renormalization group study of an order parameter field theory for the Anderson-Mott transition shows that random-field terms appear at one-loop order. They lead to an upper critical dimension $d_{c}^{+}=6$ for this model. For $d>6$ the critical behavior is mean-field like. For $d<6$ an $\epsilon$-expansion yields exponents that coincide with those for the random-field Ising model. Implications of these results are discussed.
TL;DR: A general scaling theory for a quantum glass is developed, and critical properties of both themodynamic and transport variables in terms of it are discussed, and experiments are proposed to test the predictions of the quantum-glass scaling theory.
Abstract: We combine a recent mapping of the Anderson-Mott metal-insulator transition on a random-field problem with scaling concepts for random-field magnets to argue that disordered electrons near an Anderson-Mott transition show glasslike behavior. We first discuss attempts to interpret experimental results in terms of a conventional scaling picture, and argue that some of the difficulties encountered point towards a glassy nature of the electrons. We then develop a general scaling theory for a quantum glass, and discuss critical properties of both themodynamic and transport variables in terms of it. Our most important conclusions are that for a correct interpretation of experiments one must distinguish between self-averaging and non-self-averaging observables, and that dynamical or temperature scaling is not of power-law type but rather activated, i.e., given by a generalized Vogel-Fulcher law. Recent mutually contradicting experimental results on Si:P are discussed in light of this, and experiments are proposed to test the predictions of our quantum-glass scaling theory.
TL;DR: In this article, a universal measure of particle packing was introduced for renormalization of the band gap and exciton state in the presence of high-density electron-hole pairs for quasi-one-dimensional, quasi-two-dimensional and three-dimensional (3D) systems.
Abstract: Renormalization of the band gap and exciton state in the presence of high-density electron-hole pairs is studied systematically for quasi-one-dimensional (q-1D), quasi-two-dimensional (q-2D), and three-dimensional (3D) systems. By introducing a universal measure of particle packing, it is shown that renormalization proceeds less effectively in lower dimensions. The exciton state disappears (Mott transition) due to the Coulomb-potential screening in the 3D system, the phase space filling in the q-1D system, and both of them in the q-2D system, although the screening is important at densities below the Mott density for every dimension.
TL;DR: In this article, the authors measured electrical conductivity, thermoelectric power, and crystallographic structure of tungsten trioxide and found that the predominant charge carriers are electrons related to nonstoichiometry in the oxygen sublattice (WO 3y ).
Abstract: Measurements of electrical conductivity, thermoelectric power, and crystallographic structure of tungsten trioxide are presented. It is found that the predominant charge carriers are electrons related to nonstoichiometry in the oxygen sublattice (WO 3-y ). At y = 0.1 the investigated material undergoes a semiconductor metal transition of Mott type.
TL;DR: In this paper, the authors reviewed the present understanding of the connection between the electronic structure and the crystallographic behaviour of the lanthanide and actinide elements and concluded that the 4f electrons in α-cerium contribute most significantly to the metal bonding.
TL;DR: The structural parameters of BaCo 0.9 Ni 0.1 S 1.85 with quasi-two-dimensional electrons have been determined by the X-ray Rietveld method.
Abstract: Structural parameters of BaCo 1- x Ni x S 2 (0 ≤ x ≤1) with quasi two-dimensional electrons have been determined by the X-ray Rietveld method. This sulfide exhibits the Mott transition with varying x . The interatomic distance between Co/Ni and S(1) at the apex site of a Co 1- x Ni x S 5 square-pyramid increases with x , which is consistent with the electronic configuration (3 d 3 z 2 - r 2 ) 1+ x of Co/Ni ions. The structural data of BaCo 0.9 Ni 0.1 S 1.85 show that the sulfur vacancies are within (Co/Ni)S planes.
01 Jan 1995
TL;DR: Anomalous physical properties or non-Fermi liquid behaviors around the magnetic instability in strongly correlated electron systems, such as d-metals, heavy electron systems and metallic states around the Mott transition point, are discussed in a unified way in terms of the theory of spin fluctuations.
Abstract: Anomalous physical properties or non-Fermi liquid behaviors around the magnetic instability in strongly correlated electron systems, such as d-metals, heavy electron systems and metallic states around the Mott transition point, are discussed in a unified way in terms of the theory of spin fluctuations
TL;DR: In this paper, three states of electrons on a helium film are described: diplon, an electron trapped by a positive charge located on a substrate beneath the film, the second is a variation of the first leading to the possibility of a two-dimensional metal-insulator transition, and the third is a ripplonic polaron, self-trapped in a surface dimple.
Abstract: Three novel states of electrons on a helium film are described. The first is a diplon, an electron trapped by a positive charge located on a substrate beneath the film, the second is a variation of the first leading to the possibility of a two-dimensional metal-insulator transition, and the third is a ripplonic polaron, an electron self-trapped in a surface dimple. From a survey of experimental searches for the ripplonic polaron state I conclude that no polaron transition occurs on films thicker than 14 nm at T>1.5 K.
TL;DR: In this paper, a local density linear combination of atomic orbitals method was applied to study the depostion of a K overlayer on the As-rich GaAs(100)-2\ifmmode\times\else\texttimes\fi{}4 reconstruction.
Abstract: A local-density linear combination of atomic orbitals method has been applied to study the depostion of a K overlayer on the As-rich GaAs(100)-2\ifmmode\times\else\texttimes\fi{}4 reconstruction. Our results show that the K atoms form quasi-one-dimensional structures along the missing rows of the semiconductor surface. The conduction band associated with the K orbitals is analyzed by means of an extended Hubbard Hamiltonian. We show that a Mott transition appears for a deposition of 6--7 K atoms per unit cell, and argue that for this coverage the metal-semiconductor barrier is almost completely formed.
TL;DR: Significant changes in the local atomic structure and lattice dynamics were observed by pulsed neutron inelastic scattering measurements on YBa2Cu4O8 both around the superconducting transition temperature and around the spin-gap temperature.
Abstract: Significant changes in the local atomic structure and lattice dynamics were observed by pulsed neutron inelastic scattering measurements on YBa2Cu4O8 both around the superconducting transition temperature and around the spin-gap temperature. These observations and earlier results of numerical calculations on the enhancement of electron-lattice interaction by electron correlation lead to a novel picture of unconventional lattice-induced superconductivity related to antiferroelectric instability.
TL;DR: In this article, the quantized value of conductance in a quantum wire is discussed near the Mott transition, and the way in which the quantization value collapses is also predicted as a function of temperature and length of the wire by taking account of both impurity scattering and mutual Coulomb interactions.
Abstract: The quantized value of conductance in a quantum wire is discussed near the Mott transition. The way in which the quantized value collapses is also predicted as a function of temperature and length of the wire by taking account of both impurity scattering and mutual Coulomb interactions, i.e. the case of dirty Tomonaga-Luttinger liquid.
Book•
20 Dec 1995
TL;DR: In this article, the Mott transition and the Hubbard model were used to define the coupling limit of Fermi liquid in D * 2 and Bosonization in D = 1.
Abstract: From the contents: Fermi Liquid in D * 2.- Effective Actions and the Renormalization Group.- Electronic Systems in d=1.- Bosonization. Luttinger Liquid.- Correspondence from Discrete to Continuum Models.- From Cuprate Compounds to the Hubbard Model.- The Mott Transition and the Hubbard Model.- Strong Coupling Limit and Some Exact Results.- Resonating Valence Bond States and High-Tc Superconductivity.- The Hubbard Model at D=1.- New and Old Real-Space Renormalization Group Methods for Quantum Lattice Hamiltonians.
TL;DR: In this article, the authors constructed a mean field approximation for the N-orbital Hubbard model with diagonal and non-diagonal hopping, and showed that the main role in the Mott localization-delocalization phenomenon is played by non diagonal hopping.
Abstract: Using a diagram technique for the Hubbard operators we have constructed a mean field approximation for the N-orbital Hubbard model with diagonal and non-diagonal hopping. The self-consistent renormalization of the lower and upper Hubbard subband centers, which is absent in the Hubbard I approximation, is of the order of Nt12z/U, where t1 is the diagonal hopping matrix element and z is the coordination number. This leads to different renormalizations of the Hubbard intra-atomic interaction U in the localized (Mott) phase with magnetic moment and the delocalized paramagnetic phase. The second model shows that the main role in the Mott localization-delocalization phenomenon is played by non-diagonal hopping, giving rise to two wide Hubbard subbands and 2(N − 1) narrow ones.
TL;DR: In this paper, the temperature dependence of spin correlations in the one-dimensional Hubbard model at or close to half filling by the quantum Monte Carlo method was investigated by introducing a crossover generated from an interplay of the intrinsic correlation length and the thermal correlation length.
Abstract: We investigate temperature dependence of spin correlations in the one-dimen- sional Hubbard model at or close to half filling by the quantum Monte Carlo method. The numerical data are analyzed by introducing a crossover generated from an interplay of the intrinsic correlation length and the thermal correlation length. It provides a unified picture of the spin correlation of the metallic phase near the Mott insulator at finite temperatures. Our results show that the crossover, not taken account by the conventional renormalization group and the conformal field theory, becomes more and more important to understand the spin correlation near the Mott transition point.
01 Jan 1995
TL;DR: In this paper, the Mott transition in the limit of large dimensions is studied systematically in the context of large-scale 3D models. And they describe recent results and new insights in this field.
Abstract: The Mott transition phenomena can be studied systematically in the limit of large dimensions. We describe recent results and new insights in this field.
TL;DR: In this article, the authors used second-order perturbation theory in U for the self-energy, and solved the selfconsistent equations for the local Green function of the infinite-dimensional Hubbard model.
Abstract: Using second-order perturbation theory in U for the self-energy, we solve the self-consistent equations for the local Green function of the infinite-dimensional Hubbard model. We consider the cases of Gaussian and semicircular free densities of states (DOS), and calculate the spectral densities rho ( omega ) for various U. In the semicircular case we investigate the existence of a Mott transition at half-filling. Even for large U we obtain a metallic solution. Treating the free DOS as a variable parameter, the method also gives an approximate solution of the finite-dimensional Hubbard model. We consider the case of a (regularized) logarithmic DOS appropriate for the two-dimensional case.
01 Jan 1995
TL;DR: In this article, the Mott transition phenomena can be studied systematically in the limit of large lattice spatial coordination and some results obtained with this approach are reviewed in the light of recent experiments on transition metal oxides.
Abstract: The Mott transition phenomena can be studied systematically in the limit of large lattice spatial coordination. We review some results obtained with this approach in the light of recent experiments on transition metal oxides.
TL;DR: In this paper, a model of spinless fermions on the square latticeZ2 with an interaction potential of strengthU>0 at distance one and strengthJ at distance two, in the largeU limit |t|, |J|≪U, wheret is the hopping amplitude.
Abstract: We consider a model of spinless fermions on the square latticeZ2 with an interaction potential of strengthU>0 at distance one and strengthJ at distance two, in the largeU limit |t|, |J|≪U, wheret is the hopping amplitude. As the chemical potential μ is varied, ift=T=0 we find three different phases corresponding to full, half and zero filling fractions. We study the system at low temperatureT≧0 by a method involving a canonical transformation and a functional integral representation. IfT=0 we locate the phase boundaries of the Mott metal-insulator transition for all |J|≪U with upper and lower bounds, show that mean field theory is valid ifJ 0 we have only one sided bounds for the phase boundaries and we can't validate mean field theory in caseJ<0. We introduce a new resummation scheme for low temperature expansions which yields finite and convergent perturbation series and permits us to study issues like the sign problem. Our algorithm gives an optimal canonical transformation for the functional integral such that the expectation of the sign observableS is ≧ exp\(( - c \cdot t \cdot Ve^{ - \frac{\beta }{2}} )\), whereV is the volume and β=T−1.