497 research outputs found
Exponential and power-law probability distributions of wealth and income in the United Kingdom and the United States
Lorenz curve, Gini coefficient, family income
Energy spectrum of graphene multilayers in a parallel magnetic field
We study the orbital effect of a strong magnetic field parallel to the layers
on the energy spectrum of the Bernal-stacked graphene bilayer and multilayers,
including graphite. We consider the minimal model with the electron tunneling
between the nearest sites in the plane and out of the plane. Using the
semiclassical analytical approximation and exact numerical diagonalization, we
find that the energy spectrum consists of two domains. In the low- and
high-energy domains, the semiclassical electron orbits are closed and open, so
the spectra are discrete and continuous, correspondingly. The discrete energy
levels are the analogs of the Landau levels for the parallel magnetic field.
They can be detected experimentally using electron tunneling and optical
spectroscopy. In both domains, the electron wave functions are localized on a
finite number of graphene layers, so the results can be applied to graphene
multilayers of a finite thickness.Comment: 11 pages, 13 figures. Added to v.2: Appendix A, Fig. 13, Refs.
[18-23]. V.3: minor stylistic corrections from the published versio
Hopf Term for a Two-Dimensional Electron Gas
In this Comment on the paper by W. Apel and Yu. A. Bychkov, cond-mat/9610040
and Phys. Rev. Lett. 78, 2188 (1997), we draw attention to our prior
microscopic derivations of the Hopf term for various systems and to
shortcomings of the Apel-Bychkov derivation. We explain how the value of the
Hopt term prefactor is expressed in terms of a topological invariant
in the momentum space and the quantized Hall conductivity of the system. (See
also related paper cond-mat/9703195)Comment: RevTeX, 1 page, no figure
Curie law, entropy excess, and superconductivity in heavy fermion metals and other strongly interacting Fermi liquids
Low-temperature thermodynamic properties of strongly interacting Fermi
liquids with fermion condensate are investigated. We demonstrate that the spin
susceptibility of these systems exhibits the Curie-Weiss law, and the entropy
contains a temperature-independent term. The excessive entropy is released at
the superconducting transition, enhancing the specific heat jump Delta C and
rendering it proportional to the effective Curie constant. The theoretical
results are favorably compared with the experimental data on the heavy fermion
metal CeCoIn5, as well as He-3 films.Comment: 4 pages, 2 figures. V.2: a reference added; minor changes as in the
published versio
Detecting D-Wave Pairing and Collective Modes in Fermionic Condensates with Bragg Scattering
We show how the appearance of d-wave pairing in fermionic condensates
manifests itself in inelastic light scattering. Specifically, we calculate the
Bragg scattering intensity from the dynamic structure factor and the spin
susceptibility, which can be inferred from spin flip Raman transitions. This
information provides a precise tool with which we can identify nontrivial
correlations in the state of the system beyond the information contained in the
density profile imaging alone. Due to the lack of Coulomb effects in neutral
superfluids, this is also an opportunity to observe the Anderson-Bogoliubov
collective mode
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