Searcharxiv⌕ Search

arXiv subjects

E. V. Surovtsev

Publications and source records attributed to E. V. Surovtsev.

11 recordsLinked to original sources
arXiv2026

On the Stability of the Polar Phase of Superfluid 3He in Nematic Aerogels

We study the stability of the solution corresponding to the polar phase of superfluid 3He in nematic aerogels with respect to perturbations induced by magnetic impurity scattering. We show that when the perturbation simultaneously breaks axial and time-reversal symmetry, the polar-distorted A phase is realized with the highest transition temperature. Within the proposed model of a p-wave scattering potential, which accounts for the effective spin-orbit interaction between the orbital angular momentum of a scattering quasiparticle and the magnetic moment texture of the scatterer, we solve the eigenvalue and eigenvector problem for the Gor'kov self-consistency equation. Finally, we discuss how our results relate to the available experimental data.

cond-mat.supr-con↗
arXiv2024

Drag on Cylinders Moving in Superfluid 3He-B as the Dimension Spans the Coherence Length

Vibrating probes when immersed in a fluid can provide powerful tools for characterising the surrounding medium. In superfluid 3He-B, a condensate of Cooper pairs, the dissipation arising from the scattering of quasiparticle excitations from a mechanical oscillator provides the basis of extremely sensitive thermometry and bolometry at sub-millikelvin temperatures. The unique properties of the Andreev reflection process in this condensate also assist by providing a significantly enhanced dissipation. While existing models for such damping on an oscillating cylinder have been verified experimentally, they are valid only for flows with scales much greater than the coherence length of 3He, which is of the order of a hundred nanometres. With our increasing proficiency in fabricating nanosized oscillators which can be readily used in this superfluid there is a pressing need for the development of new models that account for the modification of the flow around these smaller oscillators. Here we report preliminary results on measurements of the damping in superfluid 3He-B of a range of cylindrical nano-sized oscillators with radii comparable to the coherence length, and outline a model for calculating the associated drag.

cond-mat.mes-hall↗
arXiv2020

Oscillating nematic aerogel in superfluid 3He

We present experiments on nematic aerogel oscillating in superfluid $^3$He. This aerogel consists of nearly parallel mullite strands and is attached to a vibrating wire moving along the direction of the strands. Previous nuclear magnetic resonance experiments in $^3$He confined in similar aerogel sample have shown that the superfluid transition of $^3$He in aerogel occurs into the polar phase and the transition temperature ($T_{ca}$) is only slightly suppressed with respect to the superfluid transition temperature of bulk $^3$He. In present experiments we observed a change in resonant properties of the vibrating wire at $T=T_{ca}$ and found that below $T_{ca}$ an additional resonance mode is excited which is coupled to the main resonance.

cond-mat.other↗
arXiv2017

Local structure of ordered and disordered states of 3He-A in aerogel

Random textures of the orbital part of the order parameter of superfluid 3He-A in aerogel are analyzed theoretically in the Ginzburg and Landau region both in the presence and in the absence of a global anisotropy. Correlation functions of angles, determining orientation of the order parameter are found for relative distances which are small in comparison with the characteristic scale of the random texture. Modifications of the Larkin-Imry-Ma state in limiting cases of a relatively strong uniaxial compression and of a uniaxial stretching are analyzed and characteristic parameters of the emerging states are found.

cond-mat.supr-con↗
arXiv2015

Deformed aerogels in the superfluid 3He

Deformed aerogels induce a global anisotropy in the superfluid 3He and orient the orbital part of its order parameter. Here a phenomenological theory of the orientational effect of elastic deformations of aerogels on the superfluid phases of 3He in the spirit of conventional theory of elasticity is formulated. Phenomenological coefficients, entering basic relations, depend on properties of given aerogel in the non-deformed state. Examples of originally isotropic silica aerogel and axially symmetric "nematically ordered" aerogel are considered. Values of phenomenological coefficients are estimated with the aid of a simple microscopic model. An example of a nonuniform deformation of "nematically ordered" aerogel is discussed.

cond-mat.supr-con↗
arXiv2013

The distorted axi-planar superfluid phase of $^3$He in the "nematically ordered" aerogel

Stimulated by the results of NMR experiments with superfluid $^3$He in "nematically ordered" aerogel [1] we report on the results of phenomenological analysis of stability of different phases of superfluid $^3$He subjected to a strong homogeneous uniaxial anisotropy. On a basis of this analysis we suggest a form of the order parameter for the new ESP2 phase observed in the quoted experiments. In the weak coupling limit the suggested order parameter approaches that of the axi-planar phase. We discuss a possible experimental check of the proposed identification of the new phase.

cond-mat.dis-nn↗
arXiv2012

Coherent reaction of Fermi superfluid on correlated disorder

Motivated by the disparity between the experimentally observed properties of superfluid 3He in aerogel and predictions of the Abrikosov and Gorkov theory of superconducting alloys we consider effect of correlated pair-breaking impurities on the temperature dependence of the square of magnitude of the average order parameter and related thermodynamic properties of a Fermi superfluid. We show that the correlations, increasing the spectral density of the fluctuations with small wave vectors increase the transition temperature and enhance a temperature region below Tc where fluctuations of the order parameter dominate. Outside of this region we treat effect of impurities as a perturbation and express corrections to thermodynamic properties in terms of the structure factor of impurities. Assuming a simple model expression for correlation function of aerogel we find corrections to the temperature dependence of the NMR frequency shifts for A-like and B-like phases of 3He and compare these with experimental data.

cond-mat.dis-nn↗
arXiv2009

Low Temperature Limit of Stability of Coherent Precession of Spin in the Superfluid 3He-B

It is shown that instability of homogeneous precession is caused by combined effect of anisotropy of spin wave velocities and dipole interaction. In the principal order on the ratio of the Leggett frequency to the Larmor frequency the increments of growth of spin wave amplitudes are found. The magnitude of the maximum increment for all deviation angles of spin from its equilibrium orientation is calculated. The estimation is made of the minimum temperature down to which the precession is stable.

cond-mat.supr-con↗
arXiv2008

Orientational effect of uniaxially deformed aerogel on the order parameter of superfluid $^3He$

Effect of uniaxially-deformed aerogel on orientation of the order parameter of superfluid $^3He$ is considered. Approach used takes into account correlations in positions of particles forming aerogel. Calculations show that for the case of the B-like phase in the uniaxially-stretched aerogel deformation on the order of $10^{-2}\div10^{-4}$ is already strong enough to achieve orientation of the order parameter which is different from that required by magnetic field in bulk liquid. For the A-like phase in uniaxially-squeezed aerogel the order of magnitude of the orientational effect is estimated. It is shown that the correlations in positions of particles forming aerogel has stronger effect on the orientation of the order parameter than on the transition temperature.

cond-mat.dis-nn↗
arXiv2006

Parametric instability of homogeneous precession of spin in the superfluid 3He-B

Stability of homogeneous precession of spin due to parametric excitation of spin waves is considered as the explanation of the "catastrophic relaxation", that is observed in the superfluid 3He-B. It is shown, that at sufficiently low temperatures homogeneous precession of spin becomes unstable (Suhl instability). At zero temperature increments of growth for all spin wave modes are found. Estimation of the temperature of transition to the unstable state is made.

cond-mat.supr-con↗