Domain structure regularization in monocrystalline barium hexaferrite
Conditions for regular domain structure formation in a single-crystal barium hexaferrite plate have been studied experimentally. The purpose of the work was to develop a simple and, at the same time, effective method of regularizing the cylindrical domain structure in these plates. The cylindrical d...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2018
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| Zitieren: | Domain structure regularization in monocrystalline barium hexaferrite / A.L. Nikytenko, V.I. Kostenko, V.I. Grygoruk, V.F. Romaniuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2018. — Т. 21, № 4. — С. 402-406. — Бібліогр.: 13 назв. — англ. |
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| author | Nikytenko, A.L. Kostenko, V.I. Grygoruk, V.I. Romaniuk, V.F. |
| author_facet | Nikytenko, A.L. Kostenko, V.I. Grygoruk, V.I. Romaniuk, V.F. |
| citation_txt | Domain structure regularization in monocrystalline barium hexaferrite / A.L. Nikytenko, V.I. Kostenko, V.I. Grygoruk, V.F. Romaniuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2018. — Т. 21, № 4. — С. 402-406. — Бібліогр.: 13 назв. — англ. |
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| description | Conditions for regular domain structure formation in a single-crystal barium hexaferrite plate have been studied experimentally. The purpose of the work was to develop a simple and, at the same time, effective method of regularizing the cylindrical domain structure in these plates. The cylindrical domain structure was created by the field method, and its visualization was carried out using the Faraday effect. Radiophysical method of microwave spectroscopy was used to study characteristics of the spectra of magnetostatic oscillations, which are uniquely related to the type and quality of the formed domain structure. The method of cylindrical domain structure regularization in single-crystal barium hexaferrite has been proposed, which is based on applying a constant fixed magnetic field along the easy magnetization axis. It has been ascertained that the optimal value of the regularization field lies within the range 3.3...3.6 kOe. However, with the fields exceeding 3.6 kOe, the cylindrical domain structure is significantly distorted. It was found that the proposed method allows increasing the intensity of the highest-frequency domain magnetostatic resonance by more than 4.5 dB.
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ISSN 1560-8034, 1605-6582 (On-line), SPQEO, 2018. V. 21, N 4. P. 402-406.
© 2018, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
402
Hetero- and low-dimensional structures
Domain structure regularization in monocrystalline barium
hexaferrite
A.L. Nikytenko, V.I. Kostenko, V.I. Grygoruk, V.F. Romaniuk
Taras Shevchenko National University of Kyiv, 64, Volodymyrska Str., 01033 Kyiv, Ukraine
E-mail: art.nikitenko@gmail.com
Abstract. Conditions for regular domain structure formation in a single-crystal barium
hexaferrite plate have been studied experimentally. The purpose of the work was to develop
a simple and, at the same time, an effective method of regularizing the cylindrical domain
structure in these plates. The cylindrical domain structure was created by the field method,
and its visualization was carried out using the Faraday effect. Radiophysical method of
microwave spectroscopy was used to study characteristics of the spectra of magnetostatic
oscillations, which are uniquely related to the type and quality of the formed domain
structure. The method of cylindrical domain structure regularization in single-crystal
barium hexaferrite has been proposed, which is based on applying a constant fixed
magnetic field along the easy magnetization axis. It has been ascertained that the optimal
value of regularization field lies within the range 3.3...3.6 kOe. However, with the fields
exceeding 3.6 kOe, the cylindrical domain structure is significantly distorted. It was found
out that the proposed method allows increasing the intensity of the most high-frequency
domain magnetostatic resonance by more than 4.5 dB.
Keywords: barium hexaferrite, domain structure, single-crystal, magnetostatic oscillations.
doi: https://doi.org/10.15407/spqeo21.04.402
PACS 75.60.–d, 76.50.+g
Manuscript received 16.10.18; revised version received 09.11.18; accepted for publication
29.11.18; published online 03.12.18.
1. Introduction
Ferrites are a known class of magnetic materials, which
can be separated by three main groups: garnet, spinel,
and hexagonal ferrites. M-type hexaferrites (MFe12O19,
where M = Ba, Sr or Pb) have considerably higher value
of crystallographic anisotropy field Ha than garnets or
spinels, which allows to excite ferromagnetic resonance
(FMR) in millimeter (mm) range, even in the absence of
external magnetic fields H0 [1].
Such outstanding physical and chemical properties
of barium M-type hexaferrite (BaFe12O19) as
comparatively large values of Ha, saturation
magnetization Ms and Curie temperature, along with
corrosion resistance, excellent chemical stability and low
cost, make this material promising for many applications
including high-frequency radiation absorbers, functional
elements of the mm-range, high-capacity information
recording, sensors and various military devices [2, 3].
Being based on BaFe12O19, tunable resonators [4, 5],
insulators and radio absorbing coatings [6] have already
been developed.
It is known [7] that the temporal application of
magnetic field H0 directed at a certain angle φ to the
plane of the BaFe12O19 platelet determines the resulting
type of domain structure (DS), which remains stable in
the absence of this field. At the same time, as shown in
[8], the type of formed DS is uniquely associated with
characteristics of the spectrum of magnetostatic
oscillations (MSO) in hexaferrite platelets. Thus, the
study of the MSO spectra for DS generated by
magnetization reversal of hexaferrite samples by the field
H0 of up to 22 kOe, in the range of angles 0° ≤ φ ≤ 90°,
showed that φ = 2° and 2°30' correspond to the most
regular cylindrical DS (CDS), provided that an easy
magnetization axis (EMA) is directed along the normal to
the plane of platelets. In this case, the magnetostatic
resonance that corresponds to the type of DS is
characterized by the highest intensity and the minimum
bandwidth [8]. It is these two conditions that provide
minimal losses in the propagation of magnetostatic
waves in the BaFe12O19 platelets, as shown
experimentally in [9]. Consequently, the issue of DS
regularization becomes of particular relevance.
In a series of experiments [10], it was found that φ
≈ 2°22' is the most optimal angle for creation of CDS.
However, because of spontaneous nature of the DS
nucleation process, it looks differently after each phase of
magnetization reversal and is accompanied by the
appearance of defects. Thus, CDS domains of different
diameters arise, which is often accompanied by violation
of the hexagonal configuration in such a manner that one
domain is surrounded by 5...8 neighbors [11].
SPQEO, 2018. V. 21, N 4. P. 402-406.
Nikytenko A.L., Kostenko V.I., Grygoruk V.I., Romaniuk V.F. Domain structure regularization in single-crystal ...
403
Fig. 1. Unregularized CDS in the hexaferrite platelet in the
absence of field H0.
40 45 50 55 60
-25
-20
-15
-10
-5
0
ω
3
ω
2
ω
1
S
1
1
,
d
B
f, GHz
Fig. 2. MSO spectra in BaFe12O19 platelet with sizes
2.3×4.9×0.04 mm and formed CDS in the initial state,
measured in absence of magnetic field H0.
The possibility of CDS regularization, that is,
bringing it to such a state, which is determined only by
the parameters of a particular sample, and not by random
processes of domains origination, is demonstrated in the
work [12]. A constant magnetic field H0 directed along
EMA (H0 = (0.8...0.9)×Hs, where Hs is a saturation field)
and a changeable modulating field Hmod = 100 Oe was
additionally applied to BaFe12O19 platelet with already
formed CDS.
This work is aimed to development of CDS
regularization method in BaFe12O19 platelets and
comparison of visualized DS with the resulting MSO
spectrum.
2. Method of CDS regularization and details of
experimental researches
The domain structure in BaFe12O19 platelet was created
using the field method by applying the electromagnet and
magnetic induction meter Ш1-8. The magnetic field
H0 ≈ 21 kOe was directed at the angle φ = 2°22' to the
surface of hexaferrite platelet, which corresponds to the
optimal conditions for CDS formation. The investigated
sample was a platelet of BaFe12O19 with the sizes
2.3×4.9 mm and thickness of the ferrite layer close to
40 µm; EMA is directed along the normal to the plane of
platelet. To ensure mechanical strength, the ferrite was
glued to a silica substrate of 100-µm thickness. DS
visualization was carried out using a computerized
infrared polarization microscope МИК-4, which is based
on the Faraday effect that takes place in the conditions of
passing infrared radiation through ferrite.
The proposed method of CDS regularization is as
follows. H0 of a value, which is less than the saturation
one Hs (that is close to 4.6 kOe for the configuration
under study), was directed along EMA of the hexaferrite
platelet with an already formed CDS. The increase of
applied field occurred gradually to a certain fixed value
Hreg – field of regularization, after which it again
decreased to zero; several similar cycles were repeated.
The increase in the value of this field results in a decrease
of the domain sizes, since magnetization of domains
occur in the opposite direction to this field. It leads to a
gradual “wiping” of domains that are abnormally small.
As a result, domains are located in the most
advantageous energy position, and the hexagonal
configuration is improved. The experiment was to find
such a value of the Hreg field, which corresponds to the
most effective CDS regularization.
Along with the visual observation, the quality of the
received CDS was also controlled by the method of
ultrahigh-frequency (microwave) spectroscopy using a
scalar network analyzer Я2Р-67 and the generators P2-68
and P2-69. The frequency dependence of the reflection
coefficient module S11 for BaFe12O19 samples was
measured on the shorted end of the rectangular
waveguide section. This dependence characterizes the
spectrum of MSO that arise in a platelet of hexaferrite
under the action of an alternating magnetic field H of an
electromagnetic wave, which propagates in a waveguide
section.
3. Results of the study and their discussion
Fig. 1 shows visualized CDS in the hexaferrite sample
under investigation in the initial state in the absence of an
external field H0. It is seen from this figure that there are
inhomogeneities in CDS, the most typical of which is
different diameters of cylindrical domains.
The measured spectrum of MSO for CDS depicted
in Fig. 1, in the absence of the field H0, is shown in
Fig. 2. The low-frequency matrix MSO mode ω1 is
observed in the samples of BaFe12O19 irrespectively of
the formed DS type, but the high-frequency domain
modes ω2 and ω3 uniquely characterize the type of DS
[13].
After several cycles of magnetization by using the
field Hreg = 3.4 kOe directed perpendicularly to the
platelet surface, the previously created DS depicted in
Fig. 1 is regularized. The resulting regularized DS is
presented in Fig. 3. It is easy to see that the unevenness
of the cylindrical domain diameters decreases
significantly, at the same time, the number of defects in
the hexagonal configuration decreases as well.
SPQEO, 2018. V. 21, N 4. P. 402-406.
Nikytenko A.L., Kostenko V.I., Grygoruk V.I., Romaniuk V.F. Domain structure regularization in single-crystal ...
404
Fig. 3. Regularized using the field Hreg = 3.4 kOe CDS in
hexaferrite in the absence of field H0.
40 45 50 55 60
-25
-20
-15
-10
-5
0
ω
3
ω
2
ω
1
S
1
1
,
d
B
f, GHz
Fig. 4. MSO spectra in BaFe12O19 platelet with sizes
2.3×4.9×0.04 mm and regularized CDS using the field Hreg =
3.4 kOe, measured in the absence of magnetic field H0.
The resulting MSO spectrum in a platelet with
regularized DS depicted in Fig. 3 is shown in Fig. 4.
Comparing the spectra for CDS in the initial state
(Fig. 2) and the regularized one (Fig. 4), one can see that
the frequencies of MSO modes remain unchanged. So,
for a regularized CDS (Fig. 4) we have fω1 = 47.45 GHz,
fω2 = 50.15 GHz and fω3 = 56.86 GHz.
The full spectrum of MSO modes frequencies in a
uniaxial plate of arbitrary thickness with CDS is
determined by the system of characteristic equations
[13]:
032
2
1
3
0 =+ω+ω+ω aaaa , (1)
054
2
3
3
2
4
1
5
0 =+ω+ω+ω+ω+ω bbbbbb . (2)
The positive solutions of the system of equations (1)
and (2) allows to obtain the frequencies of MSO modes
ω1, ω2 and ω3, which for H0 = 0 in our case (Ha = 17 kOe,
Ms = 375 G) are fω1
teor
= 47.46 GHz, fω2
teor
= 50.48 GHz
and fω3
teor
= 57.04 GHz. The insignificant difference
between the experimental frequencies of these two high-
frequency modes ω2 and ω3 with the calculations
performed indicates well-formed DS, which, however, is
not ideally cylindrical.
As can be seen from Figs. 2 and 4, in the case of
CDS regularization, there is redistribution of the
intensities of the domain modes ω2 and ω3, and the
intensity of the matrix mode ω1 increases. The intensity
of the most high-frequency domain MSO mode ω3
increased from S11 = –6.13 dB down to –10.81 dB and
became close to the intensity of the domain mode ω2,
which is –8.86 dB, that is a sign of the CDS
regularization. At the same time, the bandwidth of ω3
mode measured at 3 dB decreased from ∆f = 235.4 MHz
down to 58.7 MHz. Consequently, the visual observation
of the fact of DS regularization is confirmed by the
spectral characteristics of the MSO modes.
The result of measuring the MSO mode ω3 intensity
at H0 = 0 after CDS regularization by using different
values of Hreg fields is presented in Fig. 5. From the
obtained experimental dependence, it is seen that, with an
increase in the field of regularization up to 3.6 kOe, it is
possible to increase the intensity of the mode ω3.
0 1 2 3 4 5
0
-2
-4
-6
-8
-10
-12
S
1
1
,
d
B
H
reg
, kOe
Fig. 5. Dependence of the most high-frequency domain MSO
mode ω3 intensity on the magnitude of the regularization field
measured in the absence of H0.
Fig. 6. DS formed in the hexaferrite platelet after application of
Hreg = 4 kOe in the absence of the field H0.
SPQEO, 2018. V. 21, N 4. P. 402-406.
Nikytenko A.L., Kostenko V.I., Grygoruk V.I., Romaniuk V.F. Domain structure regularization in single-crystal ...
405
With approximation of the regularization field to
the value Hs, a gradual remagnetization of the hexaferrite
plate at the angle φ = 90° occurs, which results in
destruction of CDS and, consequently, in the decrease of
the mode ω3 intensity (Fig. 5). Depicted in Fig. 6
visualized DS after applying the field of regularization
Hreg = 4 kOe demonstrates the aforementioned
considerations. The domain structure was significantly
altered, adjacent cylindrical domains actually merged to
form strips. As a result, the frequencies of the high-
frequency modes have changed to fω2 = 51.24 GHz and
fω3 = 55.57 GHz, and the intensity of ω3 mode decreased
to S11 = –4.23 dB.
4. Conclusions
The method of CDS regularization in a single-crystal
barium hexaferrite using application of a constant
magnetic field along EMA has been proposed.
It has been shown that, in the fields of
regularization within the limits Hreg = 3...3.6 kOe, it is
possible to increase the intensity of the most high-
frequency MSO mode ω3 not less than by ∆S11 ≈ 4.5 dB.
The optimal regularization field is Hreg = 3.3...3.4 kOe.
The critical field, after which CDS begins to turn into
strips, is Hreg = 3.6 kOe.
References
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H01P 1/217 (2006.1). Sorochak A.M., Kostenko
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6. Vinnik D.A., Ustinov A.B., Zherebtsov D.A., Vitko
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characterization of flux grown Al substituted
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2015. 41, No 10. P. 12728–12733. DOI:
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7. Kojima H., Goto K. Remanent domain structures of
BaFe12O19. J. Appl. Phys. 1965. 36, No 2. P. 538–
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Authors and CV
Artem Nikytenko, born in 1991.
2014–2017 PhD student at Taras
Shevchenko National University of
Kyiv, Faculty of Radiophysics,
Electronics and Computer Systems.
Since 2017 – research engineer at the
aforementioned faculty. Authored 7
publications and 1 patent, 7 works
included to Scopus. The area of his scientific interests
includes researches of magnetostatic oscillations in single-
crystal barium hexaferrite with controlled domain
structures.
E-mail: art.nikitenko@gmail.com
Victor Kostenko, born in 1949. PhD
Phys. & Math. Sci. Deputy Director
for research and international
relations at Taras Shevchenko
National University of Kyiv, Institute
of High Technologies. Authored over
60 publications and 6 patents. The
area of his scientific interests includes
researches of millimeter wave frequency technique,
radiospectroscopy of M-type hexaferrites, physics of
magnetic phenomena.
SPQEO, 2018. V. 21, N 4. P. 402-406.
Nikytenko A.L., Kostenko V.I., Grygoruk V.I., Romaniuk V.F. Domain structure regularization in single-crystal ...
406
Valeriy Grygoruk, born in 1951.
Doctor of sciences (Phys&Math).
Professor at Taras Shevchenko
National University of Kyiv, Faculty
of Radiophysics, Electronics and
Computer Systems. Authored over
270 publications, 7 patents and 9
textbooks. The area of his scientific
interests includes researches of optical radiation
transformation in fiber optics and devices based on them,
quantum radiophysics.
Vladyslav Romaniuk, born in 1941.
Research Officer at Taras Shevchenko
National University of Kyiv,
Сryogenic Сomplex. Authored over
60 publications. The area of his
scientific interests includes researches
of spin-wave electronics, millimeter
wave frequency spectroscopy of
magnetostatic waves.
|
| id | nasplib_isofts_kiev_ua-123456789-215319 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1560-8034 |
| language | English |
| last_indexed | 2026-03-23T18:47:23Z |
| publishDate | 2018 |
| publisher | Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| record_format | dspace |
| spelling | Nikytenko, A.L. Kostenko, V.I. Grygoruk, V.I. Romaniuk, V.F. 2026-03-12T08:53:33Z 2018 Domain structure regularization in monocrystalline barium hexaferrite / A.L. Nikytenko, V.I. Kostenko, V.I. Grygoruk, V.F. Romaniuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2018. — Т. 21, № 4. — С. 402-406. — Бібліогр.: 13 назв. — англ. 1560-8034 PACS: 75.60.–d, 76.50.+g https://nasplib.isofts.kiev.ua/handle/123456789/215319 https://doi.org/10.15407/spqeo21.04.402 Conditions for regular domain structure formation in a single-crystal barium hexaferrite plate have been studied experimentally. The purpose of the work was to develop a simple and, at the same time, effective method of regularizing the cylindrical domain structure in these plates. The cylindrical domain structure was created by the field method, and its visualization was carried out using the Faraday effect. Radiophysical method of microwave spectroscopy was used to study characteristics of the spectra of magnetostatic oscillations, which are uniquely related to the type and quality of the formed domain structure. The method of cylindrical domain structure regularization in single-crystal barium hexaferrite has been proposed, which is based on applying a constant fixed magnetic field along the easy magnetization axis. It has been ascertained that the optimal value of the regularization field lies within the range 3.3...3.6 kOe. However, with the fields exceeding 3.6 kOe, the cylindrical domain structure is significantly distorted. It was found that the proposed method allows increasing the intensity of the highest-frequency domain magnetostatic resonance by more than 4.5 dB. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Hetero- and low-dimensional structures Domain structure regularization in monocrystalline barium hexaferrite Article published earlier |
| spellingShingle | Domain structure regularization in monocrystalline barium hexaferrite Nikytenko, A.L. Kostenko, V.I. Grygoruk, V.I. Romaniuk, V.F. Hetero- and low-dimensional structures |
| title | Domain structure regularization in monocrystalline barium hexaferrite |
| title_full | Domain structure regularization in monocrystalline barium hexaferrite |
| title_fullStr | Domain structure regularization in monocrystalline barium hexaferrite |
| title_full_unstemmed | Domain structure regularization in monocrystalline barium hexaferrite |
| title_short | Domain structure regularization in monocrystalline barium hexaferrite |
| title_sort | domain structure regularization in monocrystalline barium hexaferrite |
| topic | Hetero- and low-dimensional structures |
| topic_facet | Hetero- and low-dimensional structures |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/215319 |
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