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Das Sarma S

Publications and source records attributed to Das Sarma S.

At least 19 recordsLinked to original sources
PubMed2000

Where is the luttinger liquid in one-dimensional semiconductor quantum wire structures?

We present the theoretical basis for analyzing resonant Raman scattering experiments in one-dimensional systems described by the Luttinger-liquid fixed point. We make experimentally testable predictions for distinguishing Luttinger liquids from the Fermi liquid and argue that presently available quantum wire systems are not in the regime where Luttinger-liquid effects are important.

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PubMed2000

Parallel magnetic field induced giant magnetoresistance in low density quasi-two-dimensional layers

We provide a possible theoretical explanation for the recently observed giant positive magnetoresistance in high mobility low density quasi-two-dimensional electron and hole systems. Our explanation is based on the strong coupling of the parallel field to the orbital motion arising from the finite layer thickness and the large Fermi wavelength of the quasi-two-dimensional system at low carrier densities.

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PubMed2000

Dissipationless transport in low-density bilayer systems

In a bilayer electronic system the layer index may be viewed as the z component of an isospin- 1 / 2. An XY isospin-ordered ferromagnetic phase was observed in quantum Hall systems and is predicted to exist at zero magnetic field at low density. This phase is a superfluid for opposite currents in the two layers. At B = 0 the system is gapless but superfluidity is not destroyed by weak disorder. In the quantum Hall case, weak disorder generates a random gauge field which probably does not destroy superfluidity. Experimental signatures include Coulomb drag and collective mode measurements.

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PubMed2000

Extremal-point densities of interface fluctuations

We introduce and investigate the stochastic dynamics of the density of local extrema (minima and maxima) of nonequilibrium surface fluctuations. We give a number of analytic results for interface fluctuations described by linear Langevin equations, and for on-lattice, solid-on-solid surface-growth models. We show that, in spite of the nonuniversal character of the quantities studied, their behavior against the variation of the microscopic length scales can present generic features, characteristic of the macroscopic observables of the system. The quantities investigated here provide us with tools that give an unorthodox approach to the dynamics of surface morphologies: a statistical analysis from the short-wavelength end of the Fourier decomposition spectrum. In addition to surface-growth applications, our results can be used to solve the asymptotic scalability problem of massively parallel algorithms for discrete-event simulations, which are extensively used in Monte Carlo simulations on parallel architectures.

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