37 research outputs found
Quantum Critical Transport Near the Mott Transition
We perform a systematic study of incoherent transport in the high temperature
crossover region of the half-filled one-band Hubbard model. We demonstrate that
the family of resistivity curves displays characteristic quantum critical
scaling of the form , with
, and . The
corresponding -function displays a "strong coupling" form
, reflecting the peculiar mirror symmetry of the
scaling curves. This behavior, which is surprisingly similar to some
experimental findings, indicates that Mott quantum criticality may be acting as
the fundamental mechanism behind the unusual transport phenomena in many
systems near the metal-insulator transition.Comment: Published version; 4+epsilon pages, 4 figure
Typical-medium, multiple-scattering theory for disordered systems with Anderson localization
The typical medium dynamical cluster approximation (TMDCA) is reformulated in
the language of multiple scattering theory to make possible first principles
calculations of the electronic structure of substitutionally disordered alloys
including the effect of Anderson localization. The TMDCA allows for a
systematic inclusion of non-local multi-site correlations and at same time
provides an order parameter, the typical density of states, for the Anderson
localization transition. The relation between the dynamical cluster
approximation and the multiple scattering theory is analyzed, and is
illustrated for a tight-binding model.Comment: 15 pages, 11 figure
Dual Fermion Method for Disordered Electronic Systems
While the coherent potential approximation (CPA) is the prevalent method for
the study of disordered electronic systems, it fails to capture non-local
correlations and Anderson localization. To incorporate such effects, we extend
the dual fermion approach to disordered non-interacting systems using the
replica method. Results for single- and two- particle quantities show good
agreement with cluster extensions of the CPA; moreover, weak localization is
captured. As a natural extension of the CPA, our method presents an alternative
to the existing cluster theories. It can be used in various applications,
including the study of disordered interacting systems, or for the description
of non-local effects in electronic structure calculations.Comment: 5 pages, 4 figure
Fingerprints of intrinsic phase separation: magnetically doped two-dimensional electron gas
In addition to Anderson and Mott localization, intrinsic phase separation has
long been advocated as the third fundamental mechanism controlling the
doping-driven metal-insulator transitions. In electronic system, where charge
neutrality precludes global phase separation, it may lead to various
inhomogeneous states and dramaticahttp://arxiv.org/submit/215787/metadata arXiv
Submission metadatally affect transport. Here we theoretically predict the
precise experimental signatures of such phase-separation-driven metal-insulator
transitions. We show that anomalous transport is expected in an intermediate
regime around the transition, displaying very strong temperature and magnetic
field dependence, but very weak density dependence. Our predictions find
striking agreement with recent experiments on Mn-doped CdTe quantum wells, a
system where we identify the microscopic origin for intrinsic phase separation.Comment: 4+epsilon pages, 4 figure
Mean-field embedding of the dual fermion approach for correlated electron systems
To reduce the rapidly growing computational cost of the dual fermion lattice
calculation with increasing system size, we introduce two embedding schemes.
One is the real fermion embedding, and the other is the dual fermion embedding.
Our numerical tests show that the real fermion and dual fermion embedding
approaches converge to essentially the same result. The application on the
Anderson disorder and Hubbard models shows that these embedding algorithms
converge more quickly with system size as compared to the conventional dual
fermion method, for the calculation of both single-particle and two-particle
quantities.Comment: 10 pages, 10 figure
Study of off-diagonal disorder using the typical medium dynamical cluster approximation
We generalize the typical medium dynamical cluster approximation (TMDCA) and
the local Blackman, Esterling, and Berk (BEB) method for systems with
off-diagonal disorder. Using our extended formalism we perform a systematic
study of the effects of non-local disorder-induced correlations and of
off-diagonal disorder on the density of states and the mobility edge of the
Anderson localized states. We apply our method to the three-dimensional
Anderson model with configuration dependent hopping and find fast convergence
with modest cluster sizes. Our results are in good agreement with the data
obtained using exact diagonalization, and the transfer matrix and kernel
polynomial methods.Comment: 10 pages, 8 figure
A Typical Medium Dynamical Cluster Approximation for the Study of Anderson Localization in Three Dimensions
We develop a systematic typical medium dynamical cluster approximation that
provides a proper description of the Anderson localization transition in three
dimensions (3D). Our method successfully captures the localization phenomenon
both in the low and large disorder regimes, and allows us to study the
localization in different momenta cells, which renders the discovery that the
Anderson localization transition occurs in a cell-selective fashion. As a
function of cluster size, our method systematically recovers the re-entrance
behavior of the mobility edge and obtains the correct critical disorder
strength for Anderson localization in 3D.Comment: 5 Pages, 4 Figures and Supplementary Material include
Nearly frozen Coulomb Liquids
We show that very long range repulsive interactions of a generalized
Coulomb-like form , with (-dimensionality),
typically introduce very strong frustration, resulting in extreme fragility of
the charge-ordered state. An \textquotedbl{}almost frozen\textquotedbl{} liquid
then survives in a broad dynamical range above the (very low) melting
temperature which is proportional to . This
\textquotedbl{}pseudogap\textquotedbl{} phase is characterized by unusual
insulating-like, but very weakly temperature dependent transport, similar to
experimental findings in certain low carrier density systems.Comment: 5 pages,4 figure
Finite Cluster Typical Medium Theory for Disordered Electronic Systems
We use the recently developed typical medium dynamical cluster (TMDCA)
approach~[Ekuma \etal,~\textit{Phys. Rev. B \textbf{89}, 081107 (2014)}] to
perform a detailed study of the Anderson localization transition in three
dimensions for the Box, Gaussian, Lorentzian, and Binary disorder
distributions, and benchmark them with exact numerical results. Utilizing the
nonlocal hybridization function and the momentum resolved typical spectra to
characterize the localization transition in three dimensions, we demonstrate
the importance of both spatial correlations and a typical environment for the
proper characterization of the localization transition in all the disorder
distributions studied. As a function of increasing cluster size, the TMDCA
systematically recovers the re-entrance behavior of the mobility edge for
disorder distributions with finite variance, obtaining the correct critical
disorder strengths, and shows that the order parameter critical exponent for
the Anderson localization transition is universal. The TMDCA is computationally
efficient, requiring only a small cluster to obtain qualitative and
quantitative data in good agreement with numerical exact results at a fraction
of the computational cost. Our results demonstrate that the TMDCA provides a
consistent and systematic description of the Anderson localization transition.Comment: 20 Pages, 19 Figures, 3 Table