4,120 research outputs found
Luttinger Stripes in Antiferromagnets
We propose a model for the physics of stripes in antiferromagnets in which
the stripes are described by Luttinger liquids hybridized with
antiferromagnetic domains. Using bosonization techniques we study the model in
the limit where the magnetic correlation length is larger than the inter-stripe
distance and propose an explanation for the commensurate-incommensurate phase
transition seen in neutron scattering in the underdoped regime of La_{2-x} Sr_x
Cu O_4. The explanation is based on a phase to anti-phase domain transition in
the spin configuration which is associated with the transverse motion of the
stripes. Using a non-linear sigma model to describe the antiferromagnetic
regions we conjecture the crystalization of the stripes in the magnetically
ordered phase.Comment: 9 pages, Revtex, Epsf, 4 figures. To appear in the Proceedings of the
Euroconference on "Correlations in unconventional quantum liquids" in
Zeitschrift f\"ur Physik B - Condensed Matter (dedicated to the memory of Sir
Rudolph Peierls
Conductivity of suspended and non-suspended graphene at finite gate voltage
We compute the DC and the optical conductivity of graphene for finite values
of the chemical potential by taking into account the effect of disorder, due to
mid-gap states (unitary scatterers) and charged impurities, and the effect of
both optical and acoustic phonons. The disorder due to mid-gap states is
treated in the coherent potential approximation (CPA, a self-consistent
approach based on the Dyson equation), whereas that due to charged impurities
is also treated via the Dyson equation, with the self-energy computed using
second order perturbation theory. The effect of the phonons is also included
via the Dyson equation, with the self energy computed using first order
perturbation theory. The self-energy due to phonons is computed both using the
bare electronic Green's function and the full electronic Green's function,
although we show that the effect of disorder on the phonon-propagator is
negligible. Our results are in qualitative agreement with recent experiments.
Quantitative agreement could be obtained if one assumes water molelcules under
the graphene substrate. We also comment on the electron-hole asymmetry observed
in the DC conductivity of suspended graphene.Comment: 13 pages, 11 figure
The mobility and diffusion of a particle coupled to a Luttinger liquid
We study the mobility of a particle coupled to a one dimensional interacting
fermionic system, a Luttinger liquid. We bosonize the Luttinger liquid and find
the effective interaction between the particle and the bosonic system. We show
that the dynamics of this system is completely equivalent to the acoustic
polaron problem where the interaction has purely electronic origin. This
problem has a zero mode excitation, or soliton, in the strong coupling limit
which corresponds to the formation of a polarization cloud due to the
fermion-fermion interaction around the particle. We obtain that, due to the
scattering of the residual bosonic modes, the soliton has a finite mobility and
diffusion coefficient at finite temperatures which depend on the
fermion-fermion interaction. We show that at low temperatures the mobility and
the diffusion coefficient are proportional to and respectively
and at high temperatures the mobility vanishes as while the diffusion
increases as .Comment: 9 pages, Revtex, UIUC preprin
Comment on "BCS superconductivity of Dirac fermions in graphene layers"
Comment on "BCS superconductivity of Dirac fermions in graphene layers" by N.
B. Kopnin and E. B. Sonin [arXiv:0803.3772; Phys. Rev. Lett. 100, 246808
(2008)].Comment: 1.1 page
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