2,319 research outputs found
Quantum critical behaviour of the plateau-insulator transition in the quantum Hall regime
High-field magnetotransport experiments provide an excellent tool to
investigate the plateau-insulator phase transition in the integral quantum Hall
effect. Here we review recent low-temperature high-field magnetotransport
studies carried out on several InGaAs/InP heterostructures and an InGaAs/GaAs
quantum well. We find that the longitudinal resistivity near the
critical filling factor ~ 0.5 follows the universal scaling law
, where . The critical exponent equals ,
which indicates that the plateau-insulator transition falls in a non-Fermi
liquid universality class.Comment: 8 pages, accepted for publication in Proceedings of the Yamada
Conference LX on Research in High Magnetic Fields (August 16-19, 2006,
Sendai
Broken symmetry, hyper-fermions, and universal conductance in transport through a fractional quantum Hall edge
We have found solution to a model of tunneling between a multi-channel Fermi
liquid reservoir and an edge of the principal fractional quantum Hall liquid
(FQHL) in the strong coupling limit. The solution explains how the absence of
the time-reversal symmetry at high energies due to chiral edge propagation
makes the universal two-terminal conductance of the FQHL fractionally quantized
and different from that of a 1D Tomonaga-Luttinger liquid wire, where a similar
model but preserving the time-reversal symmetry predicts unsuppressed
free-electron conductance.Comment: 5 twocolumn pages in RevTex, no figures, more explanations added, a
short version was published in JETP Letters, vol.74, 87 (2001
Zero-Point Fluctuations and the Quenching of the Persistent Current in Normal Metal Rings
The ground state of a phase-coherent mesoscopic system is sensitive to its
environment. We investigate the persistent current of a ring with a quantum dot
which is capacitively coupled to an external circuit with a dissipative
impedance. At zero temperature, zero-point quantum fluctuations lead to a
strong suppression of the persistent current with decreasing external
impedance. We emphasize the role of displacement currents in the dynamical
fluctuations of the persistent current and show that with decreasing external
impedance the fluctuations exceed the average persistent current.Comment: 4 pages, 2 eps figure
Is there a renormalization of the 1D conductance in Luttinger Liquid model?
Properties of 1D transport strongly depend on the proper choice of boundary
conditions. It has been frequently stated that the Luttinger Liquid (LL)
conductance is renormalized by the interaction as . To
contest this result I develop a model of 1D LL wire with the interaction
switching off at the infinities. Its solution shows that there is no
renormalization of the universal conductance while the electrons have a free
behavior in the source and drain reservoirs.Comment: 5 pages, RevTex 2.0, attempted repair of tex error
Interaction Constants and Dynamic Conductance of a Gated Wire
We show that the interaction constant governing the long-range
electron-electron interaction in a quantum wire coupled to two reservoirs and
capacitively coupled to a gate can be determined by a low frequency
measurement. We present a self-consistent, charge and current conserving theory
of the full conductance matrix. The collective excitation spectrum consists of
plasma modes with a relaxation rate which increases with the interaction
strength and is inversely proportional to the length of the wire. The
interaction parameter is determined by the first two coefficients of the
out-of-phase component of the dynamic conductance measured at the gate.Comment: 4 pages, LaTeX, 2 figure
Negative local resistance caused by viscous electron backflow in graphene
Graphene hosts a unique electron system in which electron-phonon scattering
is extremely weak but electron-electron collisions are sufficiently frequent to
provide local equilibrium above liquid nitrogen temperature. Under these
conditions, electrons can behave as a viscous liquid and exhibit hydrodynamic
phenomena similar to classical liquids. Here we report strong evidence for this
transport regime. We find that doped graphene exhibits an anomalous (negative)
voltage drop near current injection contacts, which is attributed to the
formation of submicrometer-size whirlpools in the electron flow. The viscosity
of graphene's electron liquid is found to be ~0.1 m /s, an order of
magnitude larger than that of honey, in agreement with many-body theory. Our
work shows a possibility to study electron hydrodynamics using high quality
graphene
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