Head of the Department: Professor Yurii F.KOMNIK Doctor of Sciences (Physics and Mathematics)
Tel: +(380)-57-330-85-63
Fax: +(380)-57-340-33-70
E-mail: komnik@ilt.kharkov.ua
The Department was established in 1969 amalgamating research groups studying electron transport phenomena in metals with Academician B.I.Verkin at head.
The basic scientific trends pursued in the Department are studies of various fine effects in electron transport related to the interaction of conduction electrons with phonons, electrons, impurities, defects and crystal boundaries. The objects investigated are metal and semimetal single crystals, thin films, disordered and inhomogeneous metal systems including amorphous condensates.
During different periods of time the scientific problems
solved in the Department included:
the electron-phonon interaction and drag effects in normal
metals;
effect of quasiparticle interactions and boundaries on the
kinetic properties of semimetals;
oscillatory magnetoresistive effects in semimetals;
effects of nonequilibrium phonon generation in semimetals during
supersonic drift of charge carriers;
quantum size effect in thin films;
surface carrier scattering study by the method of transverse
electron focusing;
quantum interference effects in two-dimensional metal systems;
nonlinear and nonstationary effects in metals related to the
formation of temperature-electric domains or instabilities in the regime
of nonequilibrium phonon generation;
effect of electron overheating in thin layers;
the properties and coordination structure of amorphous metal and
metal-hydrogen condensates;
transport phenomena in disordered metals far off and near the
metal-insulator transition, and so on.
Many pioneering studies performed in the Department have given
results of prime importance. Yu.F.Komnik and E.I.Buchstab were
among the first to observe the quantum size effect in Bi films.
They detected this effect in Sb films and quantum-size
oscillations of the critical temperature of superconductivity in
tin films (1970).
Yu.F.Komnik, E.I.Buchstab and V.V.Andrievskii found an anomalous
size effect in the Bi film conductivity, which is related to the
surface bending of the potential in semimetals (1975).
Yu.F.Komnik, E.I.Buchstab and Yu.V.Nikitin revealed concentration
quantum-size oscillations in thin films of Bi-Sb alloys (1977).
Yu.F.Komnik, E.I.Buchstab and A.V.Butenko performed the first
observation of the effects of weak electron localization and the
electron-electron interaction in small-thickness Bi and Sb films
and showed the possibility of separating the effects of weak
localization and electron-electron interaction (1982).
Yu.F.Komnik and B.I.Belevtsev found correlation of the
conductivity and superconducting temperature Tc of amorphous metallic
films with their coordination structure, and detected the
phenomenon of structural relaxation in amorphous condensates
(1972-1973). They also detected the formation of frozen
metastable states in low temperature condensates of metals and
metal-hydrogen systems (1982).
Yu.F.Komnik, B.I.Belevtsev and A.V.Fomin detected the reentrant
superconductivity in inhomogeneous films resulting from concurrence
of superconductivity and electron localization (1986). They
revealed the depairing effect of inelastic and phase electron
relaxation upon disordered superconductors (1988).
Yu.F.Komnik and V.Yu.Kashirin observed the effect of electron
overheating in Bi films. The studies of this effect along with the
effects of weak localization and electron-electron interaction
provided information on temperature variations of the electron-electron
and electron-phonon relaxation times (1993). They detected the
influence of a high electric field on the quantum correction to
conductivity related to the electron-electron interaction (1994).
Yu.F.Komnik, V.Yu.Kashirin, B.I.Belevtsev, E.Yu.Beliayev were the
first to detect the theoretically predicted weakening of the
electron-phonon interaction in the "dirty" limit
(1994).
B.I.Belevtsev and E.Yu.Beliayev revealed an anomalous decrease of
spin-orbit scattering rate of electrons on enhancing disorder in
Au films (1995).
Yu.F.Komnik, V.V.Andrievskii and E.I.Ace determined the energy
dependence of inelastic electron relaxation time in Bi by the
method of transverse electron focusing (1986). They found a new
method of "cyclotron spectroscopy" of the electron-phonon
relaxation in point contacts (1986).
Yu.F.Komnik, V.V.Andrievskii and S.V.Rozhok showed the
possibility of diffraction of electron flow in a point-contact(1996).
Yu.A.Bogod and V.B.Krasovitsky discovered (1975) and explained
the physical nature of "high temperature" oscillations (HTO)
of magnetoresistance in Bi and used the HTO to estimate the
spectral parameters for Bi and Bi-Sb alloys at high temperatures
and in strong magnetic fields (1982).
Yu.A.Bogod and R.G.Valeev studied transport phenomena in Bi in
the regime of nonequilibrium phonon generation during ultrasonic-rate
drift of the carriers. They revealed large-amplitude electric
oscillations related to the nonlinear regime (1975).
P.E.Finkel, V.B.Krasovitsky and S.V.Bengus developed the method
of exciting these oscillations in a wide range of magnetic fields
and temperatures (1992).
V.B.Krasovitsky and S.V.Bengus measured the transverse
galvanomagnetic (Ettingshausen) effect in bismuth single crystals and
found a sharp increase of the temperature gradient in the sample
under conditions of the supersonic drift of charge carriers
(1993).
Yu.N.Chiang and O.G.Shevchenko detected the effect of electron
drag by phonons through a non-conducting medium (1980).
Yu.N.Chiang and I.I.Logvinov were the first to realize the
N-shape I-V characteristic in a normal metal, which is related to the
formation of temperature-electric domains (1982).
Yu.N.Chiang and O.G.Shevchenko revealed the excess resistance of
the n-s boundary, which is due to the non-Andreev reflection of
the electrons sliding along the boundary (1988). They studied the
temperature-electric domain instability showing up as electric
auto-oscillations (1990).
The Department has cryostats and high-sensitivity instruments to measure the electron kinetic characteristics (conductivity, magnetic resistance, Hall-effect, thermo-emf, etc.) at low temperatures. Available are the following unique setups: 1. A precise low temperature picovoltmeter based on a superconducting modulator (the sensitivity of 1pV in a zero magnetic field and 50pV in the 20kOe magnetic field). 2. A pulsed setup to measure conductivity (20ms pulse of magnetic field up to 280kOe, 1-100mks current pulse up to 50A). 3. Ultrahigh vacuum cryostat with a superconducting solenoid and He3 for prepearing and measuring "in situ" electrical and galvanomagnetic properties of thin quench-condenced films at 0.3-350K in magnetic fields up to 50kOe (with vacuum in the chamber of 0.01- 0.1nTorr).
Prof. Yu.F.Komnik was awarded the State Prize of Ukrainian SSR, 1986. He is the author of the monograph "Physics of metallic films" (Moscow, Atomizdat Publishers, 1979).
The researchers are in active contacts with theoreticians and colleagues of other physical centers of the Ukraine, Russia, Germany, Great Britain, Netherlands, USA.
In 1996 the Department staff includes: Doctors of Sciences (Phys.- Math.) Prof. Yu.F.Komnik, Prof. Yu.N.Chiang, Dr. B.I.Belevtsev; Candidates of Sciences (Phys.-Math.) V.V.Andrievskii, V.B.Krasovitsky, V.Yu.Kashirin, O.G.Shevchenko, N.V.Dalakova, S.V.Rozhok; young researchers E.Yu.Beliayev, S.V.Bengus, I.I.Logvinov; post-graduate E.Yu.Kopeichenko.