76 research outputs found
Emergent Fermi sea in a system of interacting bosons
An understanding of the possible ways in which interactions can produce
fundamentally new emergent many-body states is a central problem of condensed
matter physics. We ask if a Fermi sea can arise in a system of bosons subject
to contact interaction. Based on exact diagonalization studies and variational
wave functions, we predict that such a state is likely to occur when a system
of two-component bosons in two dimensions, interacting via a species
independent contact interaction, is exposed to a synthetic magnetic field of
strength that corresponds to a filling factor of unity. The fermions forming
the SU(2) singlet Fermi sea are bound states of bosons and quantized vortices,
formed as a result of the repulsive interaction between bosons in the lowest
Landau level
Static and Dynamic Properties of Type-II Composite Fermion Wigner Crystals
The Wigner crystal of composite fermions is a strongly correlated state of
complex emergent particles, and therefore its unambiguous detection would be of
significant importance. Recent observation of optical resonances in the
vicinity of filling factor {\nu} = 1/3 has been interpreted as evidence for a
pinned Wigner crystal of composite fermions [Zhu et al., Phys. Rev. Lett. 105,
126803 (2010)]. We evaluate in a microscopic theory the shear modulus and the
magnetophonon and magnetoplasmon dispersions of the composite fermion Wigner
crystal in the vicinity of filling factors 1/3, 2/5, and 3/7. We determine the
region of stability of the crystal phase, and also relate the frequency of its
pinning mode to that of the corresponding electron crystal near integer
fillings. These results are in good semiquantitative agreement with experiment,
and therefore support the identification of the optical resonance as the
pinning mode of the composite fermions Wigner crystal. Our calculations also
bring out certain puzzling features, such as a relatively small melting
temperature for the composite fermion Wigner crystal, and also suggest a higher
asymmetry between Wigner crystals of composite fermion particles and holes than
that observed experimentally.Comment: Composite Fermion Wigner Crystal; 14 pages, 9 figure
Fractional quantum Hall effect arising from repulsive three body interaction
We consider a collection of fermions in a strong magnetic field coupled by a
purely three body repulsive interaction, and predict the formation of composite
fermions, leading to a remarkably rich phase diagram containing a host of
fractional quantum Hall states, a composite fermion Fermi sea, and a pairing
transition. This is entirely unexpected, because the appearance of composite
fermions and fractional quantum Hall effect is ordinarily thought to be a
result of strong two-body repulsion. Recent theoretical and experimental
breakthroughs in ultra-cold atoms and molecules have facilitated the
realization of such a system, where this physics can be tested.Comment: 4 pages, 4 figure
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