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Behnam Farid

Publications and source records attributed to Behnam Farid.

22 records · Page 2Linked to original sources
arXiv2000

Composite fermions close to the one-half filling of the lowest Landau level revisited

By strictly adhering to the microscopic theory of composite fermions (CFs) for the Landau-level filling fractions ν_e = p/(2 p + 1), we reproduce, with remarkable accuracy, the surface-acoustic-wave (SAW)-based experimental results by Willett and co-workers concerning two-dimensional electron systems with ν_e close to 1/2. Our results imply that the electron band mass m_b, as distinct from the CF mass m_*, must undergo a substantial increase under the conditions corresponding to ν_e close to 1/2. We further establish that a finite mean-free path \ell_0 is essential for the observed linearity of the longitudinal conductivity σ_{xx}(q) as deduced from the SAW velocity shifts.

cond-mat.mes-hall↗
arXiv1999

Correlated ground states with (spontaneously) broken time-reversal symmetry

We propose a self-consistent scheme for the determination of the ground-state (GS) properties of interacting electrons in a magnetic field, and of systems whose GS's time-reversal-symmetry (TRS) is spontaneously broken. It is based on a newly-developed many-body perturbation theory that is valid, irrespective of the strength of correlation, provided the GS number densities $n_{\uparrow}({\bf r})$, $n_{\downarrow}({\bf r})$, and the {\sl total} paramagnetic particle flux density are pure-state non-interacting $v$-representable. Our approach can in particular be applied to (modulated) two-dimensional electron systems in the fractional quantum-Hall regime.

cond-mat.mes-hall↗
arXiv1999

On the response of composite fermions to weak electrostatic potentials

We establish that the response to static perturbations of two-dimensional electron systems (2DESs), exposed to magnetic field B, in states with the Landau-level filling fractions νclose to one such as 1/2, is singularly different from that of 2DESs at small |B|. Thus in addition to demonstrating the sever inadequacy of the treatment of composite fermions as non-interacting particles, we show, in contradiction to a recent theoretical finding, that the physical origin of the observed behaviour of the dc longitudinal magneto-resistivity for νclose to 1/2 in periodically modulated 2DESs remains to be determined.

cond-mat.mes-hall↗