3,616 research outputs found
A brief review of recent advances on the Mott transition: unconventional transport, spectral weight transfers, and critical behaviour
Strongly correlated metals close to the Mott transition display unusual
transport regimes, together with large spectral weight transfers in optics and
photoemission. We briefly review the theoretical understanding of these
effects, based on the dynamical mean-field theory, and emphasize the key role
played by the two energy scales associated with quasiparticle coherence scale
and with the Mott gap. Recent experimental results on two-dimensional organic
compounds and transition metal oxides are considered in this perspective. The
liquid-gas critical behaviour at the Mott critical endpoint is also discussed.
Transport calculations using the numerical renormalization group are presented.Comment: Review article. 9 pages, 5 figures. Proceedings of the Vth
International Conference on Crystalline Organic Metals, Superconductors and
Magnets (ISCOM 2003
Deconfinement transition and Luttinger to Fermi Liquid crossover in quasi one-dimensional systems
We investigate a system of one dimensional Hubbard chains of interacting
fermions coupled by inter-chain hopping. Using a generalization of the
Dynamical Mean Field Theory we study the deconfinement transition from a Mott
insulator to a metal and the crossover between Luttinger and Fermi liquid
phases. One-particle properties, local spin response and inter-chain optical
conductivity are calculated. Possible applications to organic conductors are
discussed.Comment: 5 page
Equation of motion approach to the Hubbard model in infinite dimensions
We consider the Hubbard model on the infinite-dimensional Bethe lattice and
construct a systematic series of self-consistent approximations to the
one-particle Green's function, . The first
equations of motion are exactly fullfilled by and the
'th equation of motion is decoupled following a simple set of decoupling
rules. corresponds to the Hubbard-III approximation. We
present analytic and numerical results for the Mott-Hubbard transition at half
filling for .Comment: 10pager, REVTEX, 8-figures not available in postscript, manuscript
may be understood without figure
Kondo proximity effect: How does a metal penetrate into a Mott insulator?
We consider a heterostructure of a metal and a paramagnetic Mott insulator
using an adaptation of dynamical mean field theory to describe inhomogeneous
systems. The metal can penetrate into the insulator via the Kondo effect. We
investigate the scaling properties of the metal-insulator interface close to
the critical point of the Mott insulator. At criticality, the quasiparticle
weight decays as 1/x^2 with distance x from the metal within our mean field
theory. Our numerical results (using the numerical renormalization group as an
impurity solver) show that the prefactor of this power law is extremely small.Comment: 4 pages, 3 figure
Theory of a continuous Mott transition in two dimensions
We study theoretically the zero temperature phase transition in two
dimensions from a Fermi liquid to a paramagnetic Mott insulator with a spinon
Fermi surface. We show that the approach to the bandwidth controlled Mott
transition from the metallic side is accompanied by a vanishing quasiparticle
residue and a diverging effective mass. The Landau parameters
also diverge. Right at the quantum critical point there is a sharply defined
`critical Fermi surface' but no Landau quasiparticle. The critical point has a
specific heat and a non-zero resistivity. We predict
an interesting {\em universal resistivity jump} in the residual resistivity at
the critical point as the transition is approached from the metallic side. The
crossovers out of the critical region are also studied. Remarkably the initial
crossover out of criticality on the metallic side is to a Marginal Fermi Liquid
metal. At much lower temperatures there is a further crossover into the Landau
Fermi liquid. The ratio of the two crossover scales vanishes on approaching the
critical point. Similar phenomena are found in the insulating side. The filling
controlled Mott transition is also studied. Implications for experiments on the
layered triangular lattice organic material are
discussed.Comment: 14 pages, 4 figure
Chemical weathering of the volcanic soils of Isla Santa Cruz (Galápagos Islands, Ecuador)
We present a study on weathering of volcanic soils using 43 profiles (131 horizons) sampled in Santa Cruz Island (Galapagos Islands). Several weathering indices, based on chemical composition, are used. Since the geological material is highly homogeneous the intensity of weathering is mostly related to climatic conditions controlled by topography. There is a gradient of increasing weathering from the arid conditions predominant in the coast to elevations of 400-500 m a.s.l. where much more humid conditions prevail
Breakup of the Fermi surface near the Mott transition in low-dimensional systems
We investigate the Mott transition in weakly-coupled one-dimensional (1d)
fermionic chains. Using a generalization of Dynamic Mean Field Theory, we show
that the Mott gap is suppressed at some critical hopping . The
transition from the 1d insulator to a 2d metal proceeds through an intermediate
phase where the Fermi surface is broken into electron and hole pockets. The
quasiparticle spectral weight is strongly anisotropic along the Fermi surface,
both in the intermediate and metallic phases. We argue that such pockets would
look like `arcs' in photoemission experiments.Comment: REVTeX 4, 5 pages, 4 EPS figures. References added; problem with
figure 4 fixed; typos correcte
Temperature-dependent electronic structure and ferromagnetism in the d=oo Hubbard model studied by a modfied perturbation theory
The infinite-dimensional Hubbard model is studied by means of a modified
perturbation theory. The approach reduces to the iterative perturbation theory
for weak coupling. It is exact in the atomic limit and correctly reproduces the
dispersions and the weights of the Hubbard bands in the strong-coupling regime
for arbitrary fillings. Results are presented for the hyper-cubic and an
fcc-type lattice. For the latter we find ferromagnetic solutions. The
filling-dependent Curie temperature is compared with the results of a recent
Quantum Monte Carlo study.Comment: RevTeX, 5 pages, 6 eps figures included, Phys. Rev. B (in press),
Ref. 16 correcte
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