SCIENTIFIC ABSTRACT BARYAKHTAR, V. G. - BARYBIN, K.S.

• Document Type: CREST
• Collection: Scientific Abstracts
• Document Number (FOIA) /ESDN (CREST): CIA-RDP86-00513R000203810009-8
• Release Decision: RIF
• Original Classification: S
• Document Page Count: 100
• Document Creation Date: November 2, 2016
• Document Release Date: June 6, 2000
• Sequence Number: 9
• Publication Date: December 31, 1967
• Content Type: SCIENCEAB

Spin Waves in Ferromagnetios and 3/053/60/071/004/001/004
Antiferromagnetics 1 3004/B056
magnetics. In the next issue of this periodioall the last part~of'this
work will be published: II. Interaction among spin waves and between
spin waves and lattice vibrations. Relaxation processes and kinetic
processes. The authors mention apers by Ya. I. Frenkell and Ya. G.
Dorfman (Ref- 5), Ye. Lifshits Mf. 8), L. Landau and Ye. Lifshits
Ref 11~, a paper by the authors in collaboration with S. Poletminakiy
ef: 12 , V. Gurevich (Ref. 30), A. Borovik-Romanov (Refs. 39,40).
R
I. Dzyaloshinskiy (Ref- 409 Ye. Turov (Ref. 42), and N. N. Bogolyubov
and S. V. Tyablikov (Ref- 15). There are 6 figures and 55 references:
36 Soviet, 13 US, 3 British, 2 Dutch, 3 French, and 3 German.
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83985
3/053/60/072/001/001/005
B013 Bo6o
AUTHORS: kkhiyezer, A. I Barlyakhtar, V. 0 , Kaganov, M. I.
MMM-W-M- M ~ 1'. 101,~ x
Spin '~in F n IV
TITLE: Waves erromagnaticaVa d Antiferromagnetic . II
PERIODICAL: Uspekhi fizicheskikh nauk, 1960, Vol- 72, No. 1, PP- 3-32
TEXT: This is the second part of an article published in "Uspekhi
fizicheskikh nauk", 1960, Vol- 71, 533, and is devoted to the interac
-
tion of spin waves with one another and with lattice vibrationaNand.
furthermore, to the relaxation- and kinetic processes. ~ 10 deal's
with
the fusion and splitting of spin waves and their scattering on vin
waves. The authors restrict themselves to considering eleotretaNand,
therefore, take into account, aside from the interaction of 8~ in
waves
with one another, also their interaction with phonons (Ref. 1 . The
Hamiltonians of the interaction of spin waves are set up, the use of
which is restricted to the temperature range below the Curie
temperature.
The probabilities of fusion and splitting, as well as the scattering
of
spin waves, are calculated. � 11 deals with the interaction of spin
waves with lattice vibrations. The interaction of spin waves with one
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another was found to be stronger than their interaction with the lat-
tice. This allows the conclusion that the equilibrium in the spin wave
system is more quickly brought about than the one between spin waves
and
lattice. For this reason, the temperature of spin waves and lattice
may
differ. The temperature balance is disous:ed in 9 12 together with the
relaxation of the magnetic moment in eleotrets. The course of
relaxation
of the magnetic moment in eleotrets oan be explained on the basis of
the
probabilities the authors established for the interaction processes.
In
� 13, the authors deal with the dispersion of magnetic permeability of
a ferromagnetio dielectric. The complicated character of relaxation
established in the preced-in&. chapter influences the dependence of
the
electret susceptibility on frequency (Refs. 1,7). The case of a longi-
tudinal magnetic alternating field polarized along the equilibrium
mag-
netic moment is examined, i.e., the longitudinal component of magnetic
permeability is calculated. When frequencies are sufficiently high it
is more expedient not to speak of a calculation of susceptibility, but
rather of an absorption ooeffioient of the photon. This coefficient is
determined as the difference of the probabilities of all of the
absorp-
tion and emission processes of the photon. A formula for determining
the
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dependence of the photon absorption coefficient on frequency is given
(13,20); it can be applied to all limiting cases. The last chapter of
the present article ( 914) deals with the thermal conductivity of
elec-
trets. It can be calculated from the spin wave interaction Hamiltonian
and the spin wave phonon Hamiltonianp as well as the phonon - phonon
interaction Hamiltonian. There are 10 Soviet references.
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S/185/61/006/003/003/010
a4,2F,000 7/ D208/D302
AUTHORS: Barlyalchtar, V.G. and Popov, V.O.
- - -----------------------------------------
TITLE: On the thermodynamics of antiferromagnetics in a
magnetic,field
PERIODICAL: Ukrayinslkyy fizychnyy zhurnal, v. 6, no. 3, 19619
340-351
TEXT: The heat capacity and magnetization of antiferromagnetics
are calculated for a wide-range of values of magnetic field and
low temperatures; the effect of dipole-dipole interaction on the
thermodynamic characteristics of antiferromagnetics is ascertained.
Those antiferromagnetics are considered whose ma5netic moment, in
the absence of an external magnetic field, is oriented: a) along a
selected axis and b) Lies in the ground plane. In case a) (magnetic
moment of sublattices oriented along a selected axis) the thermody-
namic potential is given by:
T M( )d d0
j
d. In (I - e j
F'Tr - ~4_irl
Card 115 J-1. 2 _- 1-1.2 1 er

On the thermodynamics,
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D208/ '~302
where T is the temperature in ergs, Ej the energy of the spin wave
and dQk the elementary solid angle in the direction of the wave
vector k. The magnetization and the heat capacity are
TA Ta!g (2)
6H T2
The simplified expressions for the energy spectrum are
I J4 V Ql * DI - D2 ~2 Q2 * 72 (4)
(the terms Dj are due to the dipole interaction). The notations in
this article were adopted from (Ref. 4: V.0. Popov, Ukr. fiz. zhurn.,
6, 1, 1961). By using formulae from Ref. 4, the expressions for the
potential become 'LH RP r.
T H-S,3;. '1 [2 +qHo + 1-
e
Q lt~
T 12
(2'R)y2 a5 TSI T
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Om the thermodynamics... D20&jD302
2
T [4SLA'I J&H
. + + I _a)' *d (6) - 11
'.S -3T
13 T 5 6 T 16 T
From (5) and 6) it follows that with external fields Ho