Main results of scientific activity

1. Physics of superfluidity

Detection of a new collective mode in He II in narrow channels under conditions of partial deceleration of the normal component.
Restoration of the energy spectrum of superfluid solutions of 3He - 4He from systematic measurements of the density of the normal component and the detection of the end point of the Fermi branch of the spectrum.
Proposal and implementation of the method of studying the phase diagrams of liquid solutions of 3He in 4He using NMR.
Identification of the main dissipative processes in superfluid solutions of 3He in 4He in the waves of the first, second and fourth sounds.
Pioneering studies of the kinetics of the phonon-impurity system of superfluid solutions and the discovery of a new two-stage relaxation process.
Detection of new features of He II superfluid transfer across a film in an alternating electric field.
Determination of the anomalous dispersion of the phonon spectrum of superfluid solutions of 3He - 4He and its connection with kinetic processes.
Observation of a metastable long-living superfluid fluid and elucidation of the mechanisms of nucleation during the separation of superfluid solutions.
Detection of convective instability in stratified superfluid 3He 4He solutions when heated from the bottom.
Identification of the mechanisms of temperature and concentration relaxation in superfluid solutions of 3He - 4He at temperatures below 0.5 K.
Detection of the mechanic-electric effect in superfluid helium (appearance of an electrical response) in the presence of a temperature gradient.
Observation of turbulent flow formation and identification of dissipative processes in superfluid solutions of helium isotopes.
Detection of resonant excitation of rotons by microwave electromagnetic wave in superfluid helium.
Observation of the evolution of collective modes in superfluid helium filling a highly porous aerogel.
Identification of relaxation processes in the phonon-phonon system He II.
Observation of condensation of 3He impurities on quantized vortices in superfluid weak solutions of 3He in 4He.
Detection of intermediate flow regime in the process of formation of superfluid turbulence, due to the formation of a coil of quantized vortices of high density.

 2. Physics of quantum crystals

Discovery of the phenomenon of quantum diffusion of 3He impurities in solid mixtures of 3He in 4He.
Detection of a huge difference in the diffusion coefficients of 3He in the coexisting bcc and hcp phases of solid helium.
Establishment of the essential role of dislocations in the thermal conductivity of solid 4He and solutions of 3He - 4He.
Detection of the effect of self-localization of impurities in hcp helium crystals at low temperatures and their delocalization due to interaction with phonons under increasing temperature.
Detection of a correlation between the phase separation rate and the quantum diffusion of impuritons in 3He - 4He solid solutions;
Detection of non-monotonic temperature dependence of the decomposition rate of weak solid solutions of 3He in 4He.
Observation of anomalously fast mass transfer during dissolution of solid 3He clusters in a stratified solution of helium isotopes.
Observation of a fast diffusion process in solid solutions of 3He in 4He near the bcc hcp transition.
Detection of anomaly in the temperature dependence of the spin-lattice relaxation in the concentrated phase of the decomposed 3He - 4He solid solution.
Proof of homogeneous nucleation due to decomposition of solid 3He 4He mixtures.
Observation of Andreev Pushkarov nanoclusters consisting of 4He atoms around quasi-equilibrium vacancies.
Detection of the giant asymmetry of the processes of decay and homogenization of solutions of quantum crystals.
The first observation of multi-echo NMR in a stratified 3He - 4He solid solution.
Detection of correlation effects in the excitation subsystem due to large-scale concentration fluctuations in 3He - 4He solid solutions.
Detection of liquid-like inclusions in hardened hcp samples of 3He - 4He.
Proof of homogeneous nucleation at the bcc hcp transition in 4He. Investigation of conditions for homo- and heterogeneous nucleation.
Detection of the disordered (glass) phase in solid 4He in the supersolid region.
Determination of the mass diffusion coefficients for the decomposition of solid solutions of helium isotopes in the entire concentration range of 3He.
Observation of the evolution of the phase composition and the formation of a glass-like state in the solid helium system liquid inclusions in the region of existence of the bcc phase of solid helium.
Detection of the quantum creep mechanism of solid helium at temperatures below 0.2 K.

3. Physics of low-dimensional charged systems on the surface of liquid helium

Determination of the nature of the interaction of 3He impurities with charged particles on the basis of measuring the ion mobility in superfluid helium and solutions of 3He in 4He.
Detection of electron-ripplon interaction in a two-dimensional system of electrons over liquid helium.
Construction of the phase diagram of the liquid - electron crystal at ultra low temperatures.
The first information on the conductivity and resonance properties of an electron crystal over liquid helium in nonlinear modes was obtained.
Detection of new modes of coupled electron ripplon oscillations in a Wigner crystal on the helium surface.
Detection of a new optical mode of edge magnetoplasma oscillations in a two-dimensional electron crystal.
Implementation of a quasi-one-dimensional electron system over liquid helium and the study of its transport properties.
Detection of the effect of limited geometry on collective and kinetic phenomena in multilevel two-dimensional and one-dimensional surface electron systems over massive helium and helium film.
Creation of a generator and a highly sensitive detector of electromagnetic radiation using electrons localized above the surface of superfluid helium.
Creation of a bolometer in the infrared range, based on spectroscopic transitions of surface electrons over liquid helium.
Detection of the localization-delocalization transition in the electron layer above the superfluid helium film.
Detection of the anomalous nature of electron transfer in quasi-one-dimensional channels over superfluid helium.
Establishing the effect of the screening effects of the Coulomb interaction on the spectrum of plasma oscillations of electrons localized over a helium film.
Detection of the autolocalized state of quasi-one-dimensional surface electrons in dense helium gas.
Observation of the anomalous conductivity of electrons in quasi-one-dimensional conducting channels over liquid helium in the presence of inhomogeneous potential along the channel.
Establishment of the dependence of the nonlinear conductivity of a system of electrons over liquid helium under electron-ripplon scattering conditions.
Detection of non-equilibrium phase transitions in a two-dimensional electron crystal over liquid helium, stimulated by electric fields.
Observation of the transport of surface electrons and the formation of their autolocalized state in the system of quantum dots of a structured substrate coated with liquid helium.

4. Technique and methods of experiment at ultra low temperatures

1. Development and creation of new refrigerators for physical research at ultra-low temperatures:

continuous dilution refrigerator with adsorption pumping to temperatures of 10 mK;
copper nuclear demagnetization refrigerator for measurements up to 0.7 mK;
powerful dilution refrigerator with a hybrid circulation system at temperatures up to 5 mK;
dilution refrigerator with condensation-adsorption pumping and low-temperature circulation cycle to temperatures of 10 mK.

2. Development of original devices for low-temperature physical experiment:

miniature cryogenic pneumatic valve, dense for superfluid helium;
helium cryostat without nitrogen cooling;
anti-vibration protection system of the refrigerator;
detachable conical thermal contacts for low temperatures.

3. New methods:

method of growing high-quality crystals from superfluid helium;
osmotic method of changing the concentration of superfluid solutions directly during the experiment;
a technique for improving the quality of crystals of two-phase solid mixtures of 3He - 4He using thermal cycling in the region of phase separation;
a method for measuring ultralow diffusion values in solid mixtures of 3He - 4He using a pulsed magnetic field gradient;
method of direct measurement of the coefficient of self-diffusion in solid helium using a moving porous membrane.