2,181 research outputs found
Phase diagram of the excitonic insulator
Motivated by recent experiments, which give strong evidence for an excitonic
insulating phase in , we developed a scheme to
quantitatively construct, for generic two-band models, the phase diagram of an
excitonic insulator. As a first application of our approach, we calculated the
phase diagram for an effective mass two-band model with long-range Coulomb
interaction. The shielded potential approximation is used to derive a
generalized gap equation controlling for positive (negative) energy gaps the
transition from a semi-conducting (semi-metallic) phase to an insulating phase.
Numerical results,obtained within the quasi-static approximation, show a
steeple-like phase diagram in contrast to long-standing expectations.Comment: 2 pages, 1 figure, SCES'05, accepted for publication in Physica
Labor Law Successorship: A Corporate Law Approach
In this article, we take an approach fundamentally different from that of the labor law commentators. We start from a broader perspective than is common: successorship is as important an issue for corporate law as it is for labor law. Given that the two principal inputs to the firm are labor and capital, it would be surprising if the laws for labor law successorship were completely different from the laws for corporate law successorship. To the extent that differences exist, those differences should hinge upon differences between the employees\u27 and the creditors\u27 relationships with the firm
Sharp lines in the absorption edge of EuTe and PbEuTe in high magnetic fields
The optical absorption spectra in the region of the \fd transition energies
of epitaxial layers of of EuTe and \PbEuTe, grown by molecular beam epitaxy,
were studied using circularly polarized light, in the Faraday configuration.
Under \sigmam polarization a sharp symmetric absorption line (full width at
half-maximum 0.041 eV) emerges at the low energy side of the band-edge
absorption, for magnetic fields intensities greater than 6 T. The absorption
line shows a huge red shift (35 meV/T) with increasing magnetic fields. The
peak position of the absorption line as a function of magnetic field is
dominated by the {\em d-f} exchange interaction of the excited electron and the
\Euion spins in the lattice. The {\em d-f} exchange interaction energy was
estimated to be eV. In \PbEuTe the same absorption line
is detected, but it is broader, due to alloy disorder, indicating that the
excitation is localized within a finite radius. From a comparison of the
absorption spectra in EuTe and \PbEuTe the characteristic radius of the
excitation is estimated to be \AA.Comment: Journal of Physics: Condensed Matter (2004, at press
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