225 research outputs found
Comment on "Fluctuation-induced first-order transition p-wave superconductors" by Qi Li, D. Belitz, and J. Toner [Phys. Rev. B79, 054514 (2009)]
In this Comment, we show that the paper by Qi Li, D. Belitz and J. Toner,
published in Phys. Rev. B {\bf 79}, 054514 (2009), contains an incomplete
mean-field analysis of a simple model of Ginzburg-Landau type. The latter
contains a stable non-unitary phase, which has not been found in this study and
is missing in the outlined picture of possible stable phases. In this Comment,
the mean field analysis has been corrected, the errors have been explained in
details and relevant topics have been discussed. Shortcomings in the
mean-field-like and renormalization group studies in the mentioned paper have
also been revealed.Comment: accepted in Phys. Rev.
About phase transitions in Bose gases at constant density and constant pressure
The phase transitions in Bose gases at constant volume and constant pressure
are considered. New results for the chemical potential, the effective
Landau-Ginzburg free energy and the equation of state of the Bose condensate in
ideal Bose gases with a general form of the energy spectrum are presented.
Unresolved problems are discussed.Comment: 9 pages, no figs. AIP Proc. of Leiden Workshop (2004) on Realistic
Models of Astrophysical Matte
Meissner phases in spin-triplet ferromagnetic superconductors
We present new results for the properties of phases and phase transitions in
spin-triplet ferromagnetic superconductors. The superconductivity of the mixed
phase of coexistence of ferromagnetism and unconventional superconductivity is
triggered by the presence of spontaneous magnetization. The mixed phase is
stable but the other superconducting phases that usually exist in
unconventional superconductors are either unstable or for particular values of
the parameters of the theory some of them are metastable at relatively low
temperatures in a quite narrow domain of the phase diagram. Phase transitions
from the normal phase to the phase of coexistence is of first order while the
phase transition from the ferromagnetic phase to the coexistence phase can be
either of first or second order depending on the concrete substance. Cooper
pair and crystal anisotropies determine a more precise outline of the phase
diagram shape and reduce the degeneration of ground states of the system but
they do not change drastically phase stability domains and thermodynamic
properties of the respective phases. The results are discussed in view of
application to metallic ferromagnets as UGe2, ZrZn2, URhGe.Comment: 21 pages, 7 figures; Phys. Rev. B (2005) in pres
Diffraction field computation from arbitrarily distributed data points in space
Cataloged from PDF version of article.Computation of the diffraction field from a given set of arbitrarily distributed data points in space is an important signal
processing problem arising in digital holographic 3D displays. The field arising from such distributed data points has to be
solved simultaneously by considering all mutual couplings to get correct results. In our approach, the discrete form of the
plane wave decomposition is used to calculate the diffraction field. Two approaches, based on matrix inversion and on
projections on to convex sets (POCS), are studied. Both approaches are able to obtain the desired field when the number of
given data points is larger than the number of data points on a transverse cross-section of the space. The POCS-based
algorithm outperforms the matrix-inversion-based algorithm when the number of known data points is large.
(C) 2006 Elsevier B.V. All rights reserved
- …