222 research outputs found
Molecular-beam epitaxy of (Zn,Mn)Se on Si(100)
We have investigated the growth by molecular-beam epitaxy of the II-VI
diluted magnetic semiconductor (Zn,Mn)Se on As-passivated Si(100) substrates.
The growth start has been optimized by using low-temperature epitaxy. Surface
properties were assessed by Nomarski and scanning electron microscopy. Optical
properties of (Zn,Mn)Se have been studied by photoluminescence and a giant
Zeeman splitting of up to 30 meV has been observed. Our observations indicate a
high crystalline quality of the epitaxial films.Comment: To be published in Applied Physics Letter
BCS theory of hadronic matter at high densities
The equilibrium between the so-called 2SC and CFL phases of strange quark
matter at high densities is investigated in the framework of a simple schematic
model of the NJL type. Equal densities are assumed for quarks and .
The 2SC phase is here described by a color-flavor symmetric state, in which the
quark numbers are independent of the color-flavor combination. In the CFL phase
the quark numbers depend on the color-flavor combination, that is, the number
of quarks associated with the color-flavor combinations is different
from the number of quarks associated with the color flavor combinations
. We find that the 2SC phase is stable for a chemical
potential below GeV, while the CFL phase is stable above,
the equilibrium pressure being GeV. We have used a 3-momentum
regularizing cutoff GeV, which is somewhat larger than is usual
in NJL type models. This should be adequate if the relevant chemical potential
does not exceed 0.6 GeV.Comment: 6 figures, 13 page
Gapless phases of color-superconducting matter
We discuss gapless color superconductivity for neutral quark matter in beta
equilibrium at zero as well as at nonzero temperature. Basic properties of
gapless superconductors are reviewed. The current progress and the remaining
problems in the understanding of the phase diagram of strange quark matter are
discussed.Comment: 8 pages, 2 figures. Plenary talk at Strangeness in Quark Matter 2004
(SQM2004), Cape Town, South Africa, 15-20 September 2004. Minor correction
Two lectures on color superconductivity
The first lecture provides an introduction to the physics of color
superconductivity in cold dense quark matter. The main color superconducting
phases are briefly described and their properties are listed. The second
lecture covers recent developments in studies of color superconducting phases
in neutral and beta-equilibrated matter. The properties of gapless color
superconducting phases are discussed.Comment: 56 pages, 9 figures. Minor corrections and references added. Lectures
delivered at the IARD 2004 conference, Saas Fee, Switzerland, June 12 - 19,
2004, and at the Helmholtz International Summer School and Workshop on Hot
points in Astrophysics and Cosmology, JINR, Dubna, Russia, August 2 - 13,
200
Static perfect fluids with Pant-Sah equations of state
We analyze the 3-parameter family of exact, regular, static, spherically
symmetric perfect fluid solutions of Einstein's equations (corresponding to a
2-parameter family of equations of state) due to Pant and Sah and
"rediscovered" by Rosquist and the present author. Except for the Buchdahl
solutions which are contained as a limiting case, the fluids have finite radius
and are physically realistic for suitable parameter ranges. The equations of
state can be characterized geometrically by the property that the 3-metric on
the static slices, rescaled conformally with the fourth power of any linear
function of the norm of the static Killing vector, has constant scalar
curvature. This local property does not require spherical symmetry; in fact it
simplifies the the proof of spherical symmetry of asymptotically flat solutions
which we recall here for the Pant-Sah equations of state. We also consider a
model in Newtonian theory with analogous geometric and physical properties,
together with a proof of spherical symmetry of the asymptotically flat
solutions.Comment: 32 p., Latex, minor changes and correction
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