Curriculum vitae
and main results of Professor Dr. Yurii E. Lozovik


Institution:
Institute for Spectroscopy, Russian Academy of Sciences.
142190, Troitsk, Moscow region, Russia.
Phone: (+7-495)334-08-81
Fax:     (+7-495)334-08-86
E-mail: lozovik<@>isan.troitsk.ru, lozovik<@>mail.ru 

Present position
Head of Laboratory of Spectroscopy of Nanostructures of Institute for Spectroscopy and also Professor of Physics in Moscow Institute of Physics and Technology – Technological University (joint position).

Awards
2001 - 2004 and 1998-2000 - The Russian State Fellowship for Outstanding Scientists, prize for best publication in 2002 in Russian scientific journals. According to ISI one of most cited scientists of Russia (see also www.scientific.ru).

Scientific results
More than 500 published papers (including 10 reviews and collective monographs) devoted to  nanostructures, low-dimensional electron systems, nanotechnology, nanooptics, different aspects of solid state physics, atomic and cluster physics, nanotechnology, quantum electrodynamics in a cavity and ultrafast and near field optics .

Teaching
Tutor more than 30 PhD theses. Lecture courses: Quantum optics, Mesoscopics, Solid State Physics, Quantum electrodynamics, Computational physics, etc.

Grants and contracts
Yu.E. Lozovik was leader of team in grants (and contracts) of Eurocommunity,
NATO, Sweden; his team participated also in grants CRDF (USA), MWO (Netherland).

Conferences
Invited and plenary talks at International conferences on photonics, quantum optics, laser physics, nanostructures. Lectures at Fermi School (Italy), Goteborg University etc.
The member of International Advisory Committees for:  the 15-th, 16-th International Conferences on the Electronic Properties of Two-Dimensional Systems, 3rd International Symposium on Advanced Biomaterials/Biomechanics; member of Organizing Committees and Vice-Chairman of International Conferences on Physics of Clusters, forthcoming Conference of strong coupled plasma.

Scientific Societies and Councils
Member of scientific councils of Institute of Spectroscopy, Moscow Institute of Physics and Technology (Technological University), was Co-chairman of Moscow Union of Scientists.

Main results

Low-dimensional systems. Nanostructures
1. Electron-hole systems

1.    The superfluidity, Josephson-type effects (in nonsuperconducting systems!), drag effects, anomalous behavior in external magnetic fields, some unusual coherent optical properties and phase diagram  for the spatially separated electron-hole systems were predicted for the first time. The theory of Bose-condensation and superfluidity of 2D excitons in traps and in random fields was developed. These papers open the very perspective physics of coherent phenomena in exciton system in coupled quantum wells and dipole excitons in single quantum wells in strong normal electric field.  Theory of strongly correlated exciton liquid in the form of generalized DFT theory with spontaneous breaking of symmetry. Now in this region of investigation very interesting experimental results were obtained (Groups of D.Snoke, L.V.Butov, V.B.Timofeev etc.).
2.    The theory of two-dimensional electron-hole system in strong magnetic fields was developed. Theory of two-dimensional magnetoexcitons was developed.   The exact solution for the many-body problem of 2D electron-hole system in strong magnetic field was obtained: the ground state at any Landau level filling and any form of interaction (e.g. on taking into account image forces) due to supersymmetry is Bose condensed ideal (!) gas of magnetoexcitons. The class of exact solutions for analogous systems were obtained. Phase diagram, excitations and thermodynamics of the system were studied. The thermodynamics, excitations and some other properties of nonideal system (when interaction between electrons and holes are slightly nonsymmetrical or due to (small at high magnetic fields) contribution of virtual transitions to higher Landau levels) was studied. The papers occurred to be starting point for a set of brilliant experimental and theoretical works in the field.
3.    Bose condensation and effects of strong correlations  of exciton systems in traps, quantum dots, coupled quantum dots (quantum dot molecules) etc., in particular, in strong magnetic fields were considered. Strongly correlated phases were analyzed. Phase diagram of mesoscopic quantum exciton system was studied.
4.    Dispersion curves of two-dimensional magnetoexcitons were analyzed for the first time. It was shown that at asymptotically high magnetic fields magnetoexcitons effective mass is proportional to square root of magnetic field and it does not depend on bare electron and hole effective masses but determined only by electron-hole interaction. It was shown also that excited magnetoexciton dispersion curve is nonmonotonous function of (magnetic) momentum, i.e. “roton” minima were predicted for magnetoexciton dispersion curve. These results are in agreement with later experiments.
5.    The dispersion engineering of interwell excitons and luminescence control by parallel magnetic field were proposed and experimentally realized. This gives the possibility to determine experimentally the exciton dispersion law (with the help of fluorescence) and the dependence of the exciton mass on the magnetic field. It was shown that in strong magnetic fields, in accordance with our theory the magnetoexciton effective mass at high magnetic fields is much greater than sum of the electron and hole band masses. The instant transformation of exciton in weak fixed magnetic field to magnetoexciton (corresponding to high effective magnetic field regime) with the increase of the exciton momentum was studied.
6.    Dispersion engineering of spatially indirect excitons in the coupled quantum wells by external electric and magnetic fields in order to generate coherent acoustic phonons, to control exciton luminescence and to detect Bose condensate of excitons was proposed.
7.    The system of interacting spatially-separated excitons and electrons, particularly in the presence of Bose-condensate of excitons was analyzed. The kinetic properties of the system connected with electron-exciton drag effects have been studied. The expressions for linear response coefficients of the electron subsystem to the quantities magnitudes determining nonequlibrium state in the subsystem of excitons have been obtained.  Experimental observation of these drag  effects can give new information about the phase state of excitons by study the electric response in the electron layer and, moreover, give a new way of control of excitons with the use of electrons transport.
8.    New nonlinear optical effects for exciton coherent phase, laser stimulated backscattering and anomalous transmission were predicted. Quantum optics of coherent phase of excitons has been studied. The presence of angular correlation of photons due to coherent recombination of two or several excitons from Bose-condensate which can be studied in Hanbury Brown-Twiss- type experiments has been predicted. The observation of these effects can serve as experimental criteria of exciton phase coherence.
9.     Effects of strong correlations in 2D exciton system were studied in detail.
 Supersolid phase in mesoscopic exciton systems which possesses simultaneously transverse elasticity and superfluidity (or diagonal and nondiagonal order) was studied for the first time.

Low-dimensional systems. Nanostructures
2. Electron systems

1.    Magnetic field induced electron crystallization in 2D system based on suppression of zero-point oscillation by the field was predicted for the first time. The phase diagram and the oscillation spectra for 2D Wigner crystal in high magnetic field was calculated both from first principles and phenomenologically and also by computer simulations. Image forces influence on the phase diagram was analyzed. The set of these papers gave the first example of the influence of magnetic field on phases of 2D electron system and initiated many interesting theoretical and experimental works in physics of 2D electron gas.
2.    Crystallization of mesoscopic electron systems was studied in detail. Many-stage phase transitions, intershell orientational melting and subsequent radial shell melting were revealed for the first time. The connection of these phenomena with smallness of energy barriers relative to intershell rotation relative to intershell electron jump was revealed.
3.    Frequency dependent linear response of 2D electron system in strong magnetic fields and drift resonances (and edge excitations) in quantum Hall regime was investigated for the first time. It has been shown that it represents the properties of fractal contours of random potential. The phenomena of drift resonance in this system on the example of motion along equipotentials on Fermi level has been predicted. The microscopic theory of edge magnetoplasmons, based on the generalized random-phase approximation which take into account all diagrams of the same order on small parameter of the problem was developed.
4.    The ground state and one-particle excitations, composite fermions at half-filled Landau level for two-dimensional electron gas with anisotropic band-mass tensor were studied. Using asymptotic Ward identities of Chern-Simons theory it was shown that the composite fermions Fermi surface is not renormalized by infrared gauge fluctuations. Thus its form is identical to that of an anisotropic electron Fermi surface in the absence of the magnetic field. It appears, however, that, despite the anisotropy of the Fermi surface, the composite fermions effective mass is almost isotropic. Possible experimental consequences of these effects were predicted.
5.    Quantum Hall effect has been considered in drift approach. The connection between quantized Hall conductance and geometrical topological invariant in the system has been revealed. The drift resonance in 2D system of electrons in strong magnetic fields connected with resonance excitation of drift boundary currents along external and internal boundaries of the system was analyzed in detail. It has been shown that it represents the properties of fractal contours of random potential.
6.    The BCS-type instability of a bilayer system of composite fermions (at half Landau level filling) has been considered. The influence of composite fermion marginality due to strong correlation effects (the absence of weakly damping excitations near the Fermi surface) on BCS pairing has been analyzed. The competition of (composite) spatially separated electron-hole with electron-electron pairing controlled by interlayer separation was analyzed.

Solid State Physics. General Problems

1.    Weak localization of excitons, plasmons and their spectra in disordered systems was considered.
2.    The theory of collective excitations in slightly inhomogeneous electron gas  in inhomogeneous and disordered system was developed.
3.    Weak localization of particles with random effective mass was studied.
4.    New methods for the phonon laser creation were studied.
5.    The approach analogous to adopted in polymer molecule rearrangement was applied to study phase transitions in a set of different physical systems described by XY –model. The connection between fractal dimensionality of essential topological excitations in the system and critical indexes  of phase transition was analyzed.
6.    The self-consistent theory of anharmonic crystals and their melting was developed The theory take into account skeleton diagrams which have the same order on Lindemann parameter. The ab initio theory predicts melting points and behavior of transverse phonons as function of the temperature and quantum parameter. The results obtained are in good agreement with the numerical simulations for 2D crystals and with experimental results for Wigner and dipole crystals. The existence of some almost universal parameters (such as Lindemann parameter etc.) for crystal was explained. Empirical melting criterion, particularly Lindemann criterion was generalized and proved for the two-dimensional systems (usual Lindemann criterion is of no use for two dimensions, because the mean squared displacement of a particle from the crystal site diverges in thermodynamical limit ).

Superconductuctivity

1.    Superconducting phase transition in granular two-dimensional systems was studied. Effects of quantum phase fluctuations were studied in detail. We proposed a new model describing the quantum fluctuations of the order parameter phases in the arrays of mesoscopic superfluid and superconducting structures, and their influence on the ordered state destruction. The model employs a consistent definition of the quantum mechanical ‘phase operator’.
2.    Superconducting gap manifestation in interband optical transition was investigated both theoretically and experimentally (by time-resolved, femtosecond laser spectroscopy).
3.    Quasiparticles localization  in disordered superconductors and its influence on the thermoconductivity were studied.

Superfluidity

1.    Strongly correlated phase, mesoscopic supersolid was considered for atoms with induced dipoles or dipole excitons confined in a trap.
2.    The system of mesoscopic traps with Bose-condensate of atoms (or excitons) with Josephson coupling was considered in detail.
3.    The Bose-condensation of atoms and strong-correlation in Tonks regime in the quasi-one-dimensional traps was considered.
4.    The drag effects in two vertically coupled traps with Bose-condensed atoms were studied.

Quantum electrodynamics in a cavity

1.    Lamb shift controlling for atom in a cavity was studied. “Dynamic Lamb effect”  ( the parametric, photonless atom excitation in nonstationary cavity due to nonadiabatic   modulation of Lamb shift by cavity modulation) ¬was predicted. The effect has no relation to the dynamical Casimir effect and thus should be considered as a new vacuum quantum electrodynamical effect.
2.    Distribution and squeezing of photons generated in nonstationary cavity was calculated interaction of modes in nonstationary cavity  being taken into account.
3.    The experimental realization of dynamical Casimir effect, parametric excitation of photons in a cavity due to instantaneous change of boundary conditions induced by laser pulses or electron injection is proposed.
 Atoms, molecules

1.    Anapole (toroidal) moment of atom electron shell induced by parity nonconservation due to  weak interactions effects was predicted.
2.    Spectra of atoms, molecules and biexcitons in strong magnetic fields were studied. Paramagnetism of many-electron atoms in strong magnetic fields was considered. Thomas-Fermi equation for atoms was generalized for nonhomogeneously magnetized electron liquid in strong  magnetic fields. Magnetic dissociation of molecules   (or biexcitons) and change of the binding type in high magnetic field was predicted. This phenomena was observed experimentally for biexcitons. Magnetic field induced van der Waals binding was considered.
3.    Channelling of molecules and atoms in light fields was studied by means of computer simulation. The results can be useful to control atomic and molecular motions for driving  nanolocal  chemical reaction and also for nanotechnological applications.

Computer Simulations
 
1.    Computer simulations of set of physical systems (low-dimensional systems, clusters, cooled atoms etc. with different interparticle interactions ) study of their spectra, thermodynamical properties and phase transitions  were performed by molecular dynamics, classical and  quantum Monte Carlo, Path Integral Quantum Monte Carlo, Wigner quantum dynamics  and other techniques.
2.    Computer simulation and design of different photonic crystals by FDTD, LKKR, plane wave methods. New type of photonic crystal, superconducting photonic crystals (with photonic band spectra controlled by temperature and/or magnetic field) was studied
3.    Computer design of new materials (esp., nanomaterials and materials for photonics).
4.     Ab initio DFT simulation of nanotubes etc. Study of energy barriers, elastic and electronic properties of nanotubes.
5.    New methods of simulations of quantum systems based on quantum tomography and also Wigner formulation of quantum mechanics were developed and used in a set of physical problems: wave packet tunneling, weak localization etc. Time arrival of wave packet after passage through the tunneling barrier was studied in detail.

General problems

1.    General analysis of phase transitions in 2D systems using conformal theories was fulfilled.
2.     Equation of state for anyons (quasiparticles with fractional statistics) was analyzed.
3.    Analytical, nonperturbative approaches to  few-body quantum systems based on e-expansion near the space dimension d=2, as well as the 1/d-expansion, where d is the space dimensionality were developed.
4.     Mechanism of quark confinement was proposed based on stochastic behavior of gluon field and Anderson localization in corresponding disordered effective potential.

Nanotechnology

1.    Nanolithography and nanolocal optical study based on irradiation of tip of scanning tunneling microscope by ultrashort laser pulses  were studied. The method demonstrates the possibility of ultradense laser writing (λ/40 where λ is wavelength).   Detailed calculations of local resonances and spatial distributions of optical fields near tip of STM were performed . The method uses nanolocal “bright spot” under STM tip originated from “lightning rod” effect and excitation of local plasmon resonance. It is proposed to use this effect also for providing nanolocal chemical reactions, for nanolocal coherent control of molecules and biological objects, for linear and nonlinear optical and spectroscopy study with high spatial resolution.

Quantum dots

1. New topological phase (new Berry phase) for 2D quantum dots with odd number of electrons is revealed. The theory is in agreement with experiments on q dots with three electrons in strong magnetic field.
 2. The consistent microscopic theory of collective excitations in quantum dos and arrays of quantum dots in strong magnetic fields based on generalized RPA (taking into account all diagrams of the same order on small dimensionless parameter characterizing the dot)  has been developed. The phenomena of drift resonance in that system on the example of Fermi equipotentials of random potential on Fermi level has been predicted.
3. Strong correlated electron liquid state in quantum dot  based  on summing of expansion on deviation from electron crystallized state was studied.
4. Spin state transformation of quantum dot molecules was studied

NEMS

1.    Nanomechanics connected with relative motion of nanotube shells was developed. Regimes of work of NEMS (nanoelectromechanical systems) were analyzed.
2.    New types of NEMS based on nanotubes were proposed: nanothermometer, nanovaristor, nanoswitch, memory elements etc.

Clusters, nanoparticles, nanotubes

1.    Shell structure and structural rearrangement in different clusters were analyzed in detail. Two-stage melting was discovered in classical and quantum many-shell clusters (orientational melting, which leads to relative reorientation of “crystallized” shells and then radial melting, resulting in disappearance of shells). Potential barriers for relative rotation of shells of carbon nanoparticles and many-shell nanotubes have been studied.  It was found that two-stage melting is connected with smallness of potential barrier between neighbor shells (originated from their incommensurability) in comparison with potential barrier relating to jump of particle between the shells.
2.    Topological classification of spherical molecules and clusters was developed.
3.    Mechanisms of the formation of new carbon molecules - fullerenes, nanoparticles, nanotubes and cones have been analyzed in detail.
4.    The dependent anomalous high diamagnetism or paramagnetism of clusters was studied.
5.    Computer simulations of spectra, thermodynamic and phase transitions of two-dimensional electronic, dipole, van der Waals and other extended systems, quantum wells, quantum dots  and clusters were performed by molecular dynamics, classical and  diffusional quantum Monte Carlo, Path Integral Quantum Monte Carlo, Wigner quantum dynamics  and other techniques.

Plasmon optics. Nanooptics

1.    New surface-sensitive method of time-resolved surface plasmon optics was proposed and experimentally realized. The nonlinear optical response connected with the synchronized excitation of two surface plasmon-polariton waves, their nonlinear interaction and photon generation with the sum frequency was studied. The dependence of this process versus the temporal delay between two laser pulses and the mutual spatial overlapping of the laser beams on the surface were studied.
2.    Anomalous scattering of electromagnetic waves on composite media consisting from particles with magnetic shell was predicted. The possibility of creation of “invisible” covering of this type was analyzed.
3.    Light backscattering in disordered  2D media due to weak localization phenomena was studied.
4.    Properties of new type of photonic crystal, superconducting photonic crystals were studied.

Ultrafast Optics

1.    Damping of  quasiparticles near the Fermi surface, Fermi-liquid properties and possible deviation from Landau description in strongly correlated electron systems (in underdoped oxide superconductors) were studied  by femtosecond pump-supercontinuum probe method.
2.     The temporal evolution of superconducting state after femtosecond laser pulse excitation was studied in detail by time- resolved, femtosecond laser spectroscopy (by pump-supercontinuum probe method).
3.    New method for determination of mobility edge in disordered materials by femtosecond pump-supercontinuum probe spectroscopy was proposed and experimentally realized. The method is based on the determination of the spectral dependence of a stretched exponential relaxation in a wide probing spectral range. The method was demonstrated for porous silicon. The spectral dependence of stretched exponential index gives the unique information about existence and position of the mobility edge in disordered materials, and thus may be used as effective tool in manifestation of the transition from localized to delocalized relaxation regime on the femtosecond time scale.
4.    Our femtosecond laser spectroscopy studies open the door for highly efficient relaxation time spectroscopy which can be sensitive tool in the cases when ordinary stationary spectroscopy can not reveal any specific behavior (e.g. near Fermi level position in metals, near mobility edge in disordered semiconductor etc.).


For last review of activity look at:


Lozovik Yu.E., Popov A.M. "Properties and nanotechnological applications of nanotubes". Report at the Scientific Session of the Physical Sciences Division of the Russian Academy of Sciences (31 January 2007), published in Phys. Usp. 50, 749 (2007). Russian version available here.