arXiv subjects

Mukul S. Laad

Publications and source records attributed to Mukul S. Laad.

24 records · Page 2Linked to original sources

arXiv1999

Dielectric Response Near the Density-Driven Mott Transition in infinite dimensions

We study the dielectric response of correlated systems which undergo a Mott transition as a function of band filling within the dynamical mean field framework. We compute the dielectric figure of merit (DFOM), which is a measure of dielectric efficiency and an important number for potential device applications. It is suggested how the DFOM can be optimized in real transition metal oxides. The structures seen in the computed Faraday rotation are explained on the basis of the underlying local spectral density of the $d=\infty$ Hubbard model.

cond-mat.str-el↗

arXiv1999

Optical and Magneto-optical Response of a Doped Mott Insulator

We study the optical, Raman, and ac Hall response of the doped Mott insulator within the dynamical mean-field theory ($d=\infty$) for strongly correlated electron systems. The occurence of the {\it isosbectic} point in the optical conductivity is shown to be associated with the frequency dependence of the generalized charge susceptibility. We compute the Raman response, which probes the fluctuations of the "stress tensor", and show that the scattering is characterized by appreciable incoherent contributions. The calculated ac Hall constant and Hall angle also exhibit the isosbectic points. These results are also compared with those obtained for a {\it non-FL} metal in $d=\infty$. The role of low-energy coherence (FL) or incoherence (non-FL) in determining the finite frequency response of strongly correlated metals in $d=\infty$ is discussed in detail.

cond-mat.str-el↗

arXiv1999

Non-local effects in the fermion Dynamical mean field framework. Application to the 2D Falicov-Kimball model

We propose a new, controlled approximation scheme that explicitly includes the effects of non-local correlations on the $D=\infty$ solution. In contrast to usual $D=\infty$, the selfenergy is selfconsistently coupled to two-particle correlation functions. The formalism is general, and is applied to the two-dimensional Falicov-Kimball model. Our approach possesses all the strengths of the large-D solution, and allows one to undertake a systematic study of the effects of inclusion of k-dependent effects on the $D=\infty$ picture. Results for the density of states $ρ(ω)$, and the single particle spectral density for the 2D Falicov-Kimball model always yield positive definite $ρ(ω)$, and the spectral function shows striking new features inaccessible in $D=\infty$. Our results are in good agreement with the exact results known on the 2D Falikov-Kimball model.

cond-mat.str-el↗

arXiv1998

Theory of the ac Hall response of a model with X-ray edge Singularities in infinite dimensions

We study the ac magnetotransport in a non-Fermi liquid metal, which possesses explicit x-ray edge singularities in $d=\infty$. Specifically, we compute the ac conductivity tensor in a formalism that becomes exact in this limit. The ac Hall constant and Hall angle reveal features that are in striking qualitative agreement with those observed in optical transmission experiments carried out on $YBa_{2}Cu_{3}O_{7}$ thin films. Our results provide a concrete realization of the two-relaxation time picture proposed to explain magnetotransport anomalies in the normal state of cuprate superconductors.

cond-mat↗

arXiv1998

Theory of the temperature and doping dependence of the Hall effect in a model with x-ray edge singularities in d=oo

We explain the anomalous features in the Hall data observed experimentally in the normal state of the high-Tc superconductors. We show that a consistent treatment of the local spin fluctuations in a model with x-ray edge singularities in d=oo reproduces the temperature and the doping dependence of the Hall constant as well as the Hall angle in the normal state. The model has also been invoked to justify the marginal-Fermi-liquid behavior, and provides a consistent explanation of the Hall anomalies for a non-Fermi liquid in d=oo.

cond-mat.str-el↗

arXiv1997

Theory of the Marginal Fermi Liquid Spectrum in the Local Treatment of the Large-U Falicov-Kimball Model

The Marginal Fermi Liquid (MFL) hypothesis proposed by Varma et al is derived from a consistent treatment of local spinfluctuations in the Falicov-Kimball model (FKM). Within an infinite-dimensional mean-field approach, a marginal Fermi liquid susceptibility and single-particle self-energy are obtained near half-filling, and a Fermi liquid phase is recovered sufficiently away from half-filling, in agreement with indications from experiments which probe the normal state of the cuprates as a function of doping

cond-mat.str-el↗