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Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine

Department of Magnetic and Elastic Properties of Solids

Head of Department: Doctor of Sciences
Gennadiy E. Grechnev
tel: +(380)-57-3405011, fax: +(380)-57-3403370, e-mail: grechnev@ilt.kharkov.ua

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Last update
28.08.2012
 


Department for acoustic properties of solids

Work Team

Vyacheslav Fil
e-mail:fil@ilt.kharkov.ua
Head of group,
Principal Research Scientist,
Ph.D, professor.
Burma N.G.
Senior Research Scientist,
Ph.D.
Zvyagina G.A.
Senior Research Scientist,
Ph.D.
Zhekov K.R.
Junior Research Scientist
Bilych I.V.
1st cat. Engineer
Massalitin E.A.
Leading Engineer
Gaydamak T.N.
Ph.D. Student

The area of scientific researches

  • Electronic properties of metals in normal and superconducting states.
  • Vortex lattice dynamics in type-II superconductors.
  • Magneto elasticity; phase transitions of different nature in solids.
  • Precision measurements of the elastic modules of single crystals.

    Main results

    The extremal dimensions of Fermi surfaces of Al, Mo and Ga have been measured, the anisotropy of the energy gap in superconducting In and Al has been determined.

    The regimes of strong interaction of electrons with sound waves have been investigated. It was found that the electronic contribution to the dynamic modulus of elasticity of high-purity single crystals can reach about 10-15%.

    For the first time the effects of ballistic electron transport of elastic deformation have been detected. The method of precise measurement of extreme Fermi moment with simultaneous determination of the sign of charge carriers (Ga) was developed on this basis. The anisotropy of the velocity of the electron-electron relaxation in Al has been studied.

    Nonlinear electron-acoustic interaction in metals (the so-called pulse linearity) has been found.

    New types of electron waves that characterized y a linear dispersion law have been discovered and explored in metals: beam and cyclotron waves, zero-sound, the concentration waves. The excitation of fast magneto-sonic and Alven magneto-plasma waves has been performed in "good metals" at first. These waves previously had been observed only in Bi.

    For the first time in metals have been registered the following: a) the electric potential connected with the longitudinal sound wave; b) the inertial field accompanying the transverse sound waves. It is the acoustic analog of the Stewart-Tolman effect. Essentially new acousto-electric method for studying the dynamics of vortex lattices in type-II superconductors has been developed. The behavior of the Magnus force has been studied and parameters of the pinning potentials have been measured in borocarbides with its help. For the first time during the long history of the question the Abrikosov vortex mass (~ 10-17 g/cm, YB6) has been measured experimentally. It has appeared in two orders of magnitude larger then current theoretical estimates.

    The elastic modules of representative compounds of families of double molybdates, cuprates, borocarbides, hexa- and dodecaborides, ferroborates have been measured. In particular, a huge anisotropy of elastic properties in the basal plane of La2CuO4 single crystals was discovered. The evolution of the elastic characteristics, accompanying phase transformations ferroelastic and magnetic nature have been studied in detail for all of these compounds. A lot of these phase transitions have been discovered at first. The corresponding phase diagrams in the plane "magnetic field-temperature" have been constructed.
     

    Equipment

    One of the major achievements of the department is the development of experimental equipment which permits to carry out high-accuracy measurements of sound velocity and attenuation in strongly absorbing medium. Temperature range is 0,4-350 K, the magnetic field is up to 5.5 T. In particular, the "nonius" method, suitable for measuring the sound velocity in samples of sub-millimeter size, was created.

    The international cooperation

    • Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
    • Korea Basic Science Institute, Daejeon 305-333, Korea.
    • Institute for Solid State Physics, Technical University Dresden, Dresden D-01069, Germany.

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