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 $w^2$ 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

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

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

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 $^3$He in aerogel and for some of high-$T_c$ superconductors reveal a significant discrepancy between the observed temperatures $T_c$ 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 $T_c$ originating from spatial correlations between impurities. Analysis is limited to the Ginzburg and Landau temperature region. The shift of $T_c$ with respect to the pure material is represented as a series in concentration of the impurities $x$. In the first order on $x$ the conventional mean-field result for the lowering of $T_c$ is recovered. Contribution of correlations enters the second order term. It is expressed via the structure factor of the ensemble of impurities. For superfluid $^3$He in silica aerogel the sign of the correction corresponds to an enhancement of the $T_c$ so that the resulting pairbreaking effect of impurities is weakened. When correlation radius of impurities $R$ exceeds the coherence length of the superfluid $\xi_0$ the contribution of correlations to the shift of $T_c$ acquires a factor $\sim(R/\xi_0)^2$ and the weakening of the pairbreaking effect becomes appreciable. The presented scheme is applied to the superfluid $^3$He in aerogel.Comment: 14 pages, 1 figure, submitted to Physica Script

Gap nodes in the superconducting phase of the itinerant ferromagnet UGe2UGe_2

For the UGe$_2$ 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