2,841 research outputs found
Reply to "Comment on "Order parameter of A-like phase of 3He in aerogel"" (cond-mat/0502549)
The argument of V.P.Mineev and M.E.Zhitomirsky is based on unjustified
omission of contribution of fluctuations to the free energy of superfluid 3He
in aerogel.Comment: 3 pages, to be published in JETP Letters together with the "Comment
Analog of Anderson theorem for the polar phase of liquid 3He in nematic aerogel
It is shown that if impurities in superfluid 3He have form of infinitely long
non-magnetic strands, which are straight, parallel to each other and reflect
quasi-particles specularly, the temperature of transition of liquid 3He from
the normal into the polar phase coincides with that for the bulk liquid without
impurities. Magnetic scattering lowers transition temperature for the polar
phase in analogy with the conventional superconductors. These results are
discussed in connection with the recent experimental findings.Comment: 10 pages. Russian version will be published in ZhETF vol.154,
iss.,5(11
Longitudinal resonance and identification of the order parameter of the A-like phase of superfluid 3He in aerogel
Interpretation of the recent experiments of V.V. Dmitriev et. al. on
longitudinal resonance in the A-like phase, based on specific properties of
"robust" order parameter is proposed.Comment: 7 pages, submitted to JETP Letters, erroneous position of in
Eq. (19) is correcte
Phenomenological phase diagram of superfluid 3He in a stretched aerogel
Highly anisotropic "nematically ordered" aerogel induces global uniaxial
anisotropy in superfluid 3He. The anisotropy lowers symmetry of 3He in aerogel
from spherical to axial. As a result instead of one transition temperature in
the state, characterized by the orbital moment l=1 there are two, corresponding
to projections l_z=o and l_z=\pm 1. The splitting of transition has a
pronounced effect on the phase diagram of superfluid 3He and on a structures of
appearing phases. Possible phase diagrams, obtained phenomenologically on a
basis of Landau expansion of thermodynamic potential in a vicinity of the
transition temperature are presented here. The order parameters, corresponding
to each phase and their temperature dependencies are found.Comment: 10 pages, accepted for publication in ZhETF. A few typos are
corrected, more exact experimental data for an average diameter of a strand
is quoted in the introductio
Reply to a comment "No robust phases in aerogel..." (cond-mat/0505281)
The arguments of Volovik are refuted
Kapitza pendulum effect in a weakly disordered amorphous magnet
Effect of the "random anisotropy" type disorder on orientation of the
magnetization in an amorphous magnet is considered. It is shown, that the
principal corrections to the free energy of the magnet originate from the
fluctuations of the order parameter in the direction of its degeneracy. The
types of disorder are found, which lift the continuous degeneracy and suppress
the Larkin-Imry-Ma mechanism of disruption of the long-range order in
continuously degenerate systems.Comment: 8 pages, Russian version will be submitted to JETP Letter
Pairbreaking effect of correlated impurities in a superfluid Fermi liquid
The conventional theory of superconducting alloys does not take into account
a discreet character of impurities. Experimental data for superfluid He in
aerogel and for some of high- superconductors reveal a significant
discrepancy between the observed temperatures of their transitions in the
superfluid or superconducting state and that predicted by the theory. Here a
theoretical scheme is presented for finding corrections to the
originating from spatial correlations between impurities. Analysis is limited
to the Ginzburg and Landau temperature region. The shift of with respect
to the pure material is represented as a series in concentration of the
impurities . In the first order on the conventional mean-field result
for the lowering of is recovered. Contribution of correlations enters the
second order term. It is expressed via the structure factor of the ensemble of
impurities. For superfluid He in silica aerogel the sign of the correction
corresponds to an enhancement of the so that the resulting pairbreaking
effect of impurities is weakened. When correlation radius of impurities
exceeds the coherence length of the superfluid the contribution of
correlations to the shift of acquires a factor and the
weakening of the pairbreaking effect becomes appreciable. The presented scheme
is applied to the superfluid He in aerogel.Comment: 14 pages, 1 figure, submitted to Physica Script
Nutations of spin in the quasi-isotropic superfluid A-like phase of 3He
The order parameter of the quasi-isotropic superfluid A-like phase of 3He is
rewritten in a simple form. Effect of anisotropy of magnetic susceptibility of
this phase on the frequencies of the spatially uniform oscillations of spin and
the spin part of its order parameter are found. Anisotropy of susceptibility
has pronounced effect on the low-frequency mode, which is analogous to
nutations of the asymmetric top. Possibility of observation of the
nutation-like mode is discussed.Comment: Russian version is accepted for publication in JETP. Some words
written before in Cyrillic are replaced in the new versio
Comment on "Solution of the problem of catastrophic relaxation of homogenious spin precession in superfluid 3He-B"
The argument of Bunkov, L`vov and Volovik contains errors, making the
obtained result non-convincing.Comment: Submitted to "Pis`ma v ZhETF
Gap nodes in the superconducting phase of the itinerant ferromagnet
For the UGe ferromagnetic superconductor the forms of the order parameter
admitted by the crystal symmetry within the strong spin-orbit coupling scheme
are written down. For each of the two possible phases existence of gap nodes
required by symmetry is discussed and the nodes are found. Some consequences of
presence of the nodes, which may be useful for experimental identification of
the phases are discussed as well.Comment: 8 pages, no figures, submitted to ZhET
- …