The conductivity of the half filled Landau level. Landau Days 2014,
Channel: Taras Mogilyuk
Date: 02/07/2014

Iordanskii Sergei V., 23 June, Landau Days 2014.
"1) The theoretical description of 2DES with FQHE was developed
in a short time after the experimental discovery (1982).Initially it
was based on the assumption that the electron states must be
constructed exclusively from the states of the first Ll like the
famous Laughlin function but this approach does not give the
general description of the possible states with FQHE. Later it was
used the phenomenological Jains theory of "composite" fermions
suggesting that electrons in strong m.field are "dressed" by some
additional m.flux. That construction (and a more sophisticated
Chern-Simons field) give some part of the observed fractions
(1990) but not all.
2) In my work (2009) it was shown that the electron states with
partially filled Ll are thermodynamic unstable due to the formation
of the quantized vortices lowering the electron free energy with the
properly oriented m. moment in a fixed external m.field. This
phenomenon has a close analogy to the vortex creation in a
rotating vessel with liquid He 3 . In a large enough sample the
vortices define some vortex lattice. In a sense the vortex
singularities play the function of the additional flux of "composite"
fermions, but give the additional freedom in the physical
description of 2DES in m.field like a phase transition..."