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One-dimensional problem for S=1 with modified
antiferromagnetic Hamiltonian.
JETP Lett. 12, 225-227, 1970.
The Hamiltonian of the p-state antiferro-exchange model was proposed
and the one-dimensional exact solution was found. Too early...
Five years later B.Sutherland,
whose name the model got, re-discovered the problem.
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Spin waves in complex magnetic structures.
Sov.Phys.-JETP 34, 1387-1391, 1972 (with V.Pokrovsky).
A traditional spin excitation formalism for the system, whose ground state
consisted of several sublattices, failed. An elegant combination of
fenomenological and microscopical approaches allowed to classify all
spin excitations, and determine their long-wave spectrum.
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Magnetic properties of plane and layered systems.
Sov.Phys.-JETP 38, 847-853, 1974 (with V.Pokrovsky).
That was one of the first works on applications of the Kosterlitz-Thouless
phase transition to real layered systems. The ideas of scaling invariance
were first applied for symmetry breaking fields (two years before L.Kadanoff,
et al.)
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The dynamics of two-dimensional planar magnet.
J.Low Temp.Phys. 14, 459-470, 1974 (with A.Blank
and V.Pokrovsky).
I like this work for the non-trivial results, new at that moment,
concerning time-dependent correlation functions...
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On the properties of monolayers of adsorbed atoms.
J.Phys.C: Sol.St.Phys. 11, 3535-3549,
1978 (with V.Pokrovsky).
This work was important for understanding a mechanism of long-periodical
structures formation. In parallel, Hubbard's paper was published in Phys.Rev.B
with a similar formulation of the problem, and similar conclusions.
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ANNNI model in the magnetic field: Possible interpretation of
the CeSb phase diagram of state.
Sov.Phys.-JETP 55, 950-961, 1982
(with V.Pokrovsky).
The principal idea of the work was to map the high-temperature expansion of the free
energy onto the effective one-dimensional Hamiltonian, whose coupling constant are
temperature- and magnetic-field-dependent. A further analysis of the Hamiltonian
allowed to reproduce a rich phase diagram of CeSb.
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On magnetic phase transition in CeBi.
J.Physique 43, L 665-669, 1982.
The similar high-energy expansion of the free energy was applied to CeBi with a reasonable
agreement with experimental data.
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Two-dimensional commensurate soliton structures.
J.Physique 44, L 865-870, 1983 (with V.Pokrovsky).
Complete "devil's staircase" melting: a general topology of the phase
diagram in temperature-chemical potential(magnetic field), the shapes
transition curves, singularities on them were analyzed.
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The mechanism of the staging transitions of
graphite-intercalation compounds.
Phys. Rev.Lett. 52, 633-636,
1984 (with G.Forgacs).
My first paper published in Phys.Rev.Letters.
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Low-temperature analysis of the ANNNI model in an external
magnetic field: Cascades of phase transitions, complete devil's staircases.
J.Stat.Phys. 34, 1-34, 1984.
Low-temperature expansion of the free energy was applied to the analysis
of the ANNNI model. New features of cascades of phase transitions due to
magnetic field were reported.
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On the interface at the equilibrium crystallization.
J.Stat.Phys. 38, 191-205, 1985
(with L.Bol'shov and V.Pokrovsky).
That was an interesting attempt to apply the ideas of two-dimensional
melting of complex modulated structures to the problem of equilibrium
crystallization of solid He.
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Dynamics of vortex pairs in a two-dimensional magnetic material.
JETP Lett. 41, 128-132, 1985 (with V.Pokrovsky).
Our initial intention was to include this work as a part of the review
paper Theory of two-dimensional magnets (see it a few lines below).
But this little problem itself appeared to be original and exhibit
unexpected details...
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Two-dimensional commensurate soliton structures.
Phys.Chem.& Mech.(GB) 3, 994-1017, 1985.
That was a long version of the paper devoted to melting of two-dimensional
modulated structures. A very accurate mapping onto one-dimensional
antiferromagnetic models was done, that allowed to obtain analytical
expressions for phase boundaries and analyze a singular behavior around
them.
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Commensurate-incommensurate phase transitions and wetting in a
lattice-gas model with axially competing interaction.
Phys.Rev. B 32, 7453-7468, 1985 (with P.Rujan and W.Selke).
Two-dimensional melting in 3x1 and 4x1 modulated structures: theory versus
experiment. As often happened: theory exhibited more beautiful details than
experiment could provide us with...
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Phase transitions in two-dimensional uniformly frustrated XY
models. 1.Antiferromagnetic model on a triangular lattice.
J.Stat.Phys. 41, 1-17, 1986 (with S.Korshunov).
Fractional vortices and connected to them phase transitions. Possibilities for
phase diagrams were discussed.
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Exact solutions in the two-dimensional wetting problem.
Sov.Phys.-JETP 67, 1242-1251, 1988 (with S.Korshunov).
Mathematically, this work was a piece of art...
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On properties of localized excitations in in weakly doped
high-T_c
superconductors La_(2-x)Sr_xCuO_4.
Physica C 160, 323-327, 1989 (with V.Pokrovsky).
The ideas of percolation were applied for an attempt to explain the phase
diagram of La-based high-temperature superconductors.
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Theory of two-dimensional magnets,
in Magnetic Properties
of Layered Transition Metal Compound, 53-103, ed. by L.J. de Jongh, 1990
(with V.L.Pokrovsky).
Planned for 1985, this volume was issued five years later.
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Ferrimagnetic-helimagnetic transition in a XY magnet with
infinitely many phases.
J.Phys.: Condens.Matter 3 , 4693-4719,
1991 (with A.Pimpinelli and J.Villain).
An interesting model of helimagnet was proposed. Despite continuous symmetry
of the original model, formation of a periodic structure of
domain walls (helicity sign, the order parameter) appeared to be (free)
energetically favorable due to spin fluctuations: the so-called, Order by Disorder.
Magnetic field and temperature are the
parameters which regulate a periodicity in the domain wall ensemble.
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Dependence of T_c on the oxygen distribution in the CuO
chains in the high temperature superconductors YBa_2Cu_3O_(6+x).
Physica C 192 , 481-490, 1992 (with V.Gantmakher,
A.Neminsky, L.Novomlinsky, D.Shovkun, P.Brull).
I was the only theorist among other experimentalists: Physical properties
caused by quenching and annealing. That was the
first in a series of my works devoted to oxygen ordering in deficient planes
of YBCO.
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Role of Cu-O chains in the charge transfer mechanism in
YBa_2Cu_3O_(6+x).
Physica C 199 , 251-261, 1992
(with J.Rossat-Mignod).
The only work I did in a close collaboration with J.Rossat-Mignod.
That was a good attempt to distinguish between long and short CuO chain
fragments.
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Magnetic and other normal properties of Y-Ba-Cu-O caused by Cu-O
chain fragments.
Ann. Physik 2, 284-295,
1993 (with V.Stepanov).
One more work on the properties of constituents of oxygen deficient planes:
CuO chain fragments. We calculated microscopic quantities of chain fragments
as functions of their lengths.
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Oxygen ordering in YBa_2Cu_3O_z - a Monte Carlo
study.
Physica C 214, 37-44, 1993 (with W.Selke).
Monte Carlo simulations for YBCO in the frameworks of the ASYNNNI model.
Incorporating microscopic data for chain fragments into statistical
mechanics of CuO chain ensemble.
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Polarised neutron study of high-Tc Superconductors.
Physica B 192 , 25-38, 1993
(with J.X.Boucherle, J.Y.Henry,
R.Papoular, J.Rossat-Mignod, J.Schweizer and F.Tasset).
Again a collaboration with experimentalists: susceptibilities of
finite length chain fragments were employed to fit experimental data.
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Helimagnetism in XY models: domain walls, frustrations,
fractional vortices and phase transitions.
Phys.Rev. E
49 , 1123-1135, 1994 (with A.Pimpinelli).
That was a continuation of the work we started doing with J.Villain.
Two-dimensional helimagnets allow formation of fractional vortices attached
to domain walls!
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Order and disorder in the ensemble of Cu-O chain fragments in
oxygen deficient planes of YBa_2Cu_3O_(6+x).
Phys.Rev. B 50,
9531-9547, 1994.
A kind of summary of my former experience with YBCO, plus calculations of
diffuse scattering caused by CuO chain fragments.
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A search for the herringbone superstructure in
YBa_2Cu_3O_(6+x).
Solid State Comm. 94, 695-701, 1995
(with F.Yakhou, V.Plakhty, P.Burlet,
B.Kviatkovsky, J.Y.Henry, J.Lauriat, E.Elkaim and E.Ressouche).
Again collaboration with experimentalists. At that moment it was popular
to search for the herringbone superstructure in YBCO. Not successively,
but it did not depend on the theoretical part...
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Mode-Coupling Effects on the Quadrupolar Ordering in CeB6.
Solid State Commun. 97, 595-598, 1996 (with Y.Kuramoto and
N.Fukushima).
For me, that was a nice idea to change a subject of the interest. I was
a visitor at the Tohoku Univ in Sendai and eager to investigate this case...
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Theoretical study of Cu-O chain fragments in the oxygen-deficient planes
of
YBa_2Cu_3O_(6+x).
I. Microscopic properties.
Phys.Rev. B 53, 5872-5879,
1996
(with P.Gawiec, D.R.Grempel, A.-C.Riiser and H.Haugerud).
Quantum Monte Carlo in cooperation with Lanczos algorithm
were employed for studying the properties of CuO chains.
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Inelastic neutron scattering in CeB6.
Physics Letters A 215,
97-102, 1996.
Succeeded to explain a pseudosplitting of the ground state quartet as
a cooperative effect of quadrupolar excitations. Before it
was ascribed to non-cubic distortions in CeB6.
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Analytic theory of diffuse scattering from distributions of non-overlapping
structures.
Acta Cryst. A 53, 15-27, 1997.
(with P.-A.Lindgaard).
Incorporated the idea of application of the transfer matrix for a system
consinting of blocks of various "colors". Diffuse scattering for such a disorder
was analutically computed.
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From microscopic description to statistical mechanics of Cu-O chain fragments
in the high-T_c superconductors REBa_2Cu_3O_(6+x).
Physica C 275, 93-109, 1997 (with H.Haugerud, and W.Selke).
That was my last work on rare-earth BCO high T_c compounds. The work included
microscopic calculations for chain fragments, and incorporation of those quantities
into a statistical scheme based on Monte Carlo simulations. Calculations were performed
for Y, La, Nd BCO compounds and compared with the experimental data, many of them
due to Luetgemeier.
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Quadrupolar and magnetic ordering in CeB6.
Phys.Rev. B 55,
8267-8279, 1997.
Investigation of the CeB6 case continues! A traditional quadrupolar
interaction was probed as a candidate. It results in a very soft mode of
quadrupolar excitations. So, a spherical model instead of a mean field
becomes a proper tool for finding out the shape of the phase diagram.
Agreement with experiment is really good.
-
Model for the low-temperature magnetic phases observed in doped
YBa_2Cu_3O_(6+x).
Phys.Rev. B 56, 10840-10843, 1997
(with N.H.Andersen).
Unusual mechanism for low-tempearature magnetic transitions in doped YBCO.
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Crystal Field, Magnetic Anisotropy and Excitations in Rare-Earth
Hexaborides.
Accepted for publication in
Phys.Rev. B in August, 1999 (with W.Brenig).
15-years-old inelastic neutron measurements were analyzed. Due to the
values of the actual crystal field gaps, NdB6 must be classified as a
strong spin-quadrupolar coupling system. Observable intensities of spin
excitations appear to be wave-vector dependent.
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Low-Energy Excitations of Yb4As3 in a Magnetic Field.
Submitted to Phys.Rev.Lett., September, 1999 (with P.Fulde,
A.Ovchinnikov, and Yu.Kudasov).
Because this is my last work, it is the best...
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