arXiv subjects

K. A. Muttalib

Publications and source records attributed to K. A. Muttalib.

42 records · Page 3Linked to original sources

arXiv1999

Dielectric anomalies of solid CO and N_2 in the audio frequency range

We report the first audio frequency dielectric constant measurements of CO and N_2 in their solid phases. We have observed several new features, including (1) strong hysteresis effects above an onset temperature $T_{h} \simeq 42 K$ in the β-phase of pure N_2, (2) absence of the expected short range antiferroelectric dipolar ordering in CO down to 4.2 K, and (3) anomalous temperature dependence of the dielectric constant in the α-phases of both CO and N_2. Quantum mechanical treatment of the molecular rotation explains some of the observed anomalies in the α-phase, but the strong hysteresis indicates that pure geometrical frustration plays a significant role in the β-phase.

cond-mat.mtrl-sci↗

arXiv1997

New Class of Random Matrix Ensembles with Multifractal Eigenvectors

Three recently suggested random matrix ensembles (RME) are linked together by an exact mapping and plausible conjections. Since it is known that in one of these ensembles the eigenvector statistics is multifractal, we argue that all three ensembles belong to a new class of critical RME with multifractal eigenfunction statistics and a universal critical spectral statitics. The generic form of the two-level correlation function for weak and extremely strong multifractality is suggested. Applications to the spectral statistics at the Anderson transition and for certain systems on the border of chaos and integrability is discussed.

cond-mat↗

arXiv1995

Impact of localization on Dyson's circular ensemble

A wide variety of complex physical systems described by unitary matrices have been shown numerically to satisfy level statistics predicted by Dyson's circular ensemble. We argue that the impact of localization in such systems is to provide certain restrictions on the eigenvalues. We consider a solvable model which takes into account such restrictions qualitatively and find that within the model a gap is created in the spectrum, and there is a transition from the universal Wigner distribution towards a Poisson distribution with increasing localization.

cond-mat↗

arXiv1994

Exactly solvable random matrix models with additional two-body interactions

It has been argued that despite remarkable success, existing random matrix theories are not adequate to describe disordered conductors in the metallic regime, due to the presence of certain two-body interactions in the effective Hamiltonian for the eigenvalues, in addition to the standard logarithmic interaction that arises entirely from symmetry considerations. We present a new method that allows exact solution of random matrix models with such additional two-body interactions. This should broaden the scope of random matrix models in general.

cond-mat↗

arXiv1993

Transitions In Spectral Statistics

We present long range statistical properties of a recently introduced unitary random matrix ensemble, whose short range correlations were found to describe a transition from Wigner to Poisson type as a function of a single parameter.

cond-mat↗

arXiv1993

Crossover from Fermi Liquid to Non-Fermi Liquid Behavior in a Solvable One-Dimensional Model

We consider a quantum moany-body problem in one-dimension described by a Jastrow type, characterized by an exponent $λ$ and a parameter $γ$. We show that with increasing $γ$, the Fermi Liquid state ($γ=0)$ crosses over to non-Fermi liquid states, characterized by effective "temperature".

cond-mat↗