JOURNAL OF APPLIED PHYSICSVOLUME 88, NUMBER 5

1 SEPTEMBER 2000

Epitaxial Bi3Fe5O12„001… films grown by pulsed laser deposition
and reactive ion beam sputtering techniques
N. Adachi, V. P. Denysenkov, S. I. Khartsev, and A. M. Grishina)
Department of Condensed Matter Physics, Royal Institute of Technology, S-100 44 Stockholm, Sweden

T. Okuda
Nagoya Institute of Technology, Nagoya 466, Japan

共Received 17 December 1999; accepted for publication 24 May 2000兲
We report on processing and comparative characterization of epitaxial Bi3Fe5O12 共BIG兲 films grownonto Gd3共ScGa兲5O12关GSGG,(001)] single crystal using pulsed laser deposition 共PLD兲 and reactive
ion beam sputtering 共RIBS兲 techniques. A very high deposition rate of about 0.8 ␮m/h has beenachieved in the PLD process. Comprehensive x-ray diffraction analyses reveal epitaxial quality bothof the films: they are single phase, exclusively 共001兲 oriented, the full width at half maximum of therocking curve of 共004兲 Bragg reflection is 0.06 deg for PLD and 0.05 deg for RIBS film, strongly
in-plane textured with cube-on-cube film-to-substrate epitaxial relationship. Saturation
magnetization 4 ␲ M s and Faraday rotation at 635 nm were found to be 1400 Gs and ⫺7.8 deg/␮min PLD-BIG, and 1200 Gs and ⫺6.9 deg/␮m in RIBS-BIG. Ferromagnetic resonance 共FMR兲
measurements performed at 9.25 GHz yielded the gyromagnetic ratio ␥ ⫽1.797⫻107 l/s Oe,
43
1.826⫻107 l/s Oe; the constants of uniaxial magnetic anisotropy were K *u ⫽⫺8.66⫻10 erg/cm ,
4
3
3
3
3
3
⫺8.60⫻10 erg/cm ; the cubic magnetic anisotropy K 1 ⫽⫺2.7⫻10 erg/cm ,⫺3.8⫻10 erg/cm ;and the FMR linewidth ⌬H⫽25 and 34 Oe for PLD and RIBS films correspondingly. High Faraday
rotation, low microwave loss, and low coercive field ⭐40 Oe of BIG/GSGG共001兲 films promise
their use in integrated magneto-optic applications. © 2000 American Institute of Physics.
关S0021-8979共00兲03317-X兴

tering 共RIBS兲 technique onto Gd3共ScGa兲5O12 共GSGG兲
substrate1 and exhibited ⫺8.4 deg/␮m of Faraday rotation at
633 nm and saturation magnetization 4 ␲ M s ⫽1500 Gs. 2 In
the last decade BIG films had also been prepared by electron
cyclotron resonance 共ECR兲 sputtering and radio-frequency
共rf兲 magnetron sputtering techniques.3,4 These methods show
approximately equal results, however, all of them sufferfrom too low deposition rate to provide industrial BIG application.
Pulsed laser deposition 共PLD兲 thin film technology has
made rapid progress in recent years.5 Great success has beenachieved to grow high-T c superconducting thin films, ferroelectrics, manganite colossal magnetoresistors, high performance dielectrics, and complex oxide multilayers.6 In comparison with other techniques, PLD has great advantages
using laser radiation as a source of ‘‘pure’’ energy: film contamination can be suppressed to the lowest level while PLD
is capable of operating at relatively high gas pressure thatmight be critical for complex oxide film growth.
Two attempts to prepare BIG by PLD have been recently
reported.7,8 Films of 共111兲 BIG grown by Chern and Liaw7
exhibit Faraday rotation of ⫺5.4 deg/␮m at 633 nm and4 ␲ M s ⫽1470 Gs. Watanabe et al. fabricated 共111兲 BIG with
Faraday rotation of ⫺7.0 deg/␮m at 633 nm.8 In this article
we report on preparation and comprehensive characterizationof BIG films made by PLD and RIBS techniques to compare
films crystalline and magneto-optical properties, magnetic
performance at low and high frequencies.

I. INTRODUCTION

Completely substituted bismuth iron garnet Bi3Fe5O12
共BIG兲 films have attracted much attention for various applications in nonreciprocal and waveguide devices, based onmagnetostatic waves 共MSW兲, magneto-optical 共MO兲 isolators, and integrated MSW-MO components. Since Bi substituted yttrium iron garnet 共YIG兲 possesses enhanced Faraday
effect of ⫺2 deg/␮m at 633 nm per Bi content and low
optical losses in the visible to near infrared light region, there
were many attempts undertaken to increase Bi substitution in
Bi:YIG films made by liquid phase epitaxy. Furthermore, it
has been found that linear dependence of Faraday rotation on
Bi content changes to a superlinear one when the Bi content
exceeds two atoms per one formula unit and reaches thegiant value as high as ⫺8 deg/␮m for completely substituted
BIG.
Bi3⫹, having been substituted in dodecahedral sites ofgarnet structure, has a large ionic radius of 1.17 Å compared
to 0.95 Å of Y3⫹. This results in very strong YIG lattice
expansion with the rate of 0.083 Å/共Bi atom/formula unit兲.
At high temperatures combinatorial entropy becomes energetically favorable and makes Bi3Fe5O12 to be a thermodynamically nonequilibrium phase. This is why completely
substituted BIG has been obtained only in the form of a film
clamped on the single crystal substrate. A first time
BIG共111兲 film has been grown by a reactive ion beam sputa兲

Electronic mail: grishin@kth.se

0021-8979/2000/88(5)/2734/6/$17.00

2734© 2000 American Institute of Physics

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Adachi et al.

J. Appl. Phys., Vol. 88, No. 5, 1 September 2000

2735

TABLE I. Processing conditions for PLD and RIBS techniques.
PLD
TargetBackground pressure, Torr
Working pressure, mTorr
Substrate
Film lattice constant, ÅSubstrate temperature, °C
Deposition rate, ␮m/h

RIBS

Precursor BiFeO3 and Bi2Fe4O9 ceramics
1⫻10⫺72⫻10⫺6
5–200
0.11
Gd3共ScGa兲5O12共001兲, a⫽12.570⫾0.005 Å
12.627
12.633
550
480
0.730
0.128

III. FILMS CHARACTERIZATION

FIG. 1. X-ray diffraction 共XRD, CuK ␣ radiation兲 pattern of the target used
for pulsed laser deposition. The peaks denoted ‘‘1’’ and ‘‘2’’ correspond to
Bragg reflections from BiFeO3 共JCPDS 14-181兲 and Bi2Fe4O9 共JCPDS 25090兲 oxides, respectively.

II. FILMS SYNTHESISIn the reactive ion beam sputtering 共RIBS兲 technique,
Kaufman type ion 共usually Ar⫹兲 source is used to produce
uniform ion beam to sputter the target. Argon ions are neutralized to prevent charge accumulation on the insulating target. A reactive atmosphere for growing film oxidation isformed by supplying O2 gas in the vicinity of substrateholder. The detailed description of BIG preparation by RIBS
technique can be found in Ref. 9. Usually it takes about 10 h
to get micrometer thick BIG film.
In the PLD process, KrF excimer laser 共LPX300,
Lambda Physik, ␭⫽248 nm, pulsed energy density 2–3
J/cm2, the repetition rate 30–50 Hz兲 has been used to ablate
ceramic target. Both RIBS and PLD techniques use precursor
target, which was made from oxide powders 3⫻Bi2O3⫹5⫻Fe2O3 by cold pressing at 300 kg/cm2 and sintering at the temperature 800–900 °C for 4 h. The procedureof regrinding, pressing, and sintering was repeated twice toensure microscopic homogeneity. The density of the target is6.09 g/cm3. X-ray diffraction 共XRD兲 analysis confirms thetarget to be two phases: BiFeO3 and Bi2Fe4O9 共Fig. 1兲 withthe stoichiometric Bi:Fe ratio of 3:5, which is requested forBi3Fe5O12 garnet phase. During a deposition the target was
rotated to avoid its fast erosion and consumption.
共001兲 Gd3共ScGa兲5O12 garnet 共GSGG兲 single crystal has
been chosen as a substrate. It has a cubic lattice constant of
12.570⫾0.005 Å. Thus the mismatch between GSGG andfabricated BIG film appeared to be less than 0.5%. GSGG
wafer has been sliced into square 5⫻5 mm2 pieces andbonded to the heater by a silver paste. The substrate washeated at 650 °C before deposition for thermal cleaning of
the surface, and then during the deposition the substrate was
kept at growth temperature of 550 °C. The distance between
the substrate and the target was set at 5 cm and typical deposition time was about one hour. The oxygen pressure has
been varied from 5 to 200 mTorr. The processing conditions
used in PLD and RIBS techniques are summarized inTable I.

Both PLD and RIBS films were characterized by thesame methods using the same equipment. Film thickness wasmeasured by the atomic force microscope 共AFM, Burleigh
Personal SPM兲. To make a sharp step of the film a small partof the substrate was masked before the deposition or a smallpart of the film was etched away by the acid. Thickness ofthe films deposited by PLD and RIBS during one hour was
estimated to be 0.730 and 0.128 ␮m correspondingly, thus
the deposition rate achieved by PLD technique is six times
higher than that in RIBS technique. Both films have red colorand optically smooth surface. The optical absorption coefficient ␣ at 635 nm was measured to be 3484 cm⫺1 for bothfilms.
A Siemens D-5000 powder x-ray diffractometer with Cu
tube has been used to study the films’ crystalline structure.
XRD patterns of PLD films grown at oxygen pressure exceeding 30 mTorr show weak 共012兲 BiFeO3 Bragg peak
while films grown at lower oxygen pressure have been foundto be single Bi3Fe5O12 phase. Instead of a complicated twophase XRD pattern of the target 共Fig. 1兲, an XRD ␪ –2␪ scanof PLD-BIG/GSGG structure 共Fig. 2兲 consists of (00l)
Bragg reflections only. Cu K ␣ 1 and Cu K ␣ 2 lines from BIG
film and GSGG substrate are clearly resolved. At low incident ␪ angles the intensity of the film reflections are higher
compared with those from the substrate due to smaller x-ray
penetration depth. In logarithmic scale, besides the main
共004兲, 共008兲, 共0012兲, and 共0016兲 reflections, the weaker

FIG. 2. XRD ␪ –2␪ scans in CuK ␣ radiation for 0.73-␮m-thick
Bi3Fe5O12共BIG兲 film grown by PLD technique onto Gd3共ScGa兲5O12共GSGG兲
single crystal. 共hkl兲 peaks indicate BIG film and GSGG substrate Braggreflections. Magnified 共004兲 and 共008兲 reflections are shown in the insert.

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2736

Adachi et al.

J. Appl. Phys., Vol. 88, No. 5, 1 September 2000

FIG. 3. Same XRD patterns as in Fig. 2 for RIBS-made Bi3Fe5O12(1.28␮ m兲/Gd3共ScGa兲5O12 structure.

peaks can be recognized around 2 ␪ ⫽14°, 43°, 75°, and120°. They correspond to 共002兲, 共006兲, 共0010兲, and 共0014兲
reflections, which are forbidden in ideal crystal and attributed to the noncomplete destructive interference of x rays on
GSGG surface distorted by cutting and polishing processes.
Figure 3 shows similar ␪ –2␪ XRD patterns for BIG filmgrown onto GSGG substrate by RIBS technique.
Films’ lattice parameter a 0 has been found by plotting
a 0 against the Nelson–Riley function10

冉冊

a cos ␪ ⫺a 0
1
1
⫽C cos2 ␪⫹ ,a0
sin ␪ ␪FIG. 5. XRD patterns for 0.73-␮m-thick PLD-BIG共001兲 film: 共a兲 rocking
curves of 共004兲 Bragg reflections from Bi3Fe5O12共BIG兲 film and
Gd3共ScGa兲5O12共GSGG兲 substrate; 共b兲 ␸ scans of off-normal 共4010兲 plane in
BIG film and GSGG substrate.

共1兲

where a cos ␪ is an interplane distance calculated from the apparent Bragg peak position at 2␪ and C is a fitting coefficient. Figure 4 presents the lattice parameters a cos ␪ calculated from 共004兲, 共008兲, 共0012兲, and 共0016兲 Bragg reflections
for PLD, RIBS films as well as for GSGG substrate. The‘‘true’’ lattice parameters a 0 , obtained as an extrapolation tocos2 ␪→0, were found to be 12.574 Å for GSGG substrate,

12.627 Å for PLD-BIG film, and 12.633 Å for RIBS-BIG.
Taking into account the Bragg reflections linewidth, shownin Fig. 4 as error bars, the lattice parameters of both PLD and
RIBS films can be regarded to be the same within the experimental errors while the lattice mismatch between the BIG
films and GSGG substrate is estimated to be less than 0.5%.
The rocking curves of 共004兲 reflections of PLD and
RIBS films in comparison with GSGG substrate are shown in
Figs. 5 and 6. The full width at half maximum 共FWHM兲 is
0.06° for the PLD film and 0.05° for the RIBS film, respectively. The narrowest FWHM of PLD-BIG has beenachieved for the film grown at oxygen pressure of 10 mTorr.
We also detected Bragg reflections from off-normal 兵4010其
planes of GSGG and BIG. They are presented as ␸ scans in
Figs. 5 and 6. The optimum sample ␪ sample and the detector
2 ␪ detector positions used for ␸-scan measurements are shownin Table II. Fourfold symmetry observed in ␸ scans and strict
correspondence between diffraction peaks from film and substrate confirm epitaxial cube-on-cube relationship of
Bi3Fe5O12 on Gd3共ScGa兲5O12
共 001兲 BIG储共001兲GSGG,
关 010兴 , 关 100兴 BIG储关010兴,关100兴GSGG.

FIG. 4. Lattice parameters for Gd3共ScGa兲5O12 substrate and Bi3Fe5O12 films
grown by PLD 共symbols 䊊兲 and RIBS 共symbols 䉭兲 techniques. Lattice
parameter a cos ␪ was calculated from 共004兲, 共008兲, 共0012兲, and 共0016兲 Braggreflections position. Experimental a cos ␪ vs ␪ dependence has been fitted to
Nelson–Riley Eq. 共1兲 to extrapolate at cos ␪→0 ‘‘true’’ lattice parametersa 0 ⫽12.574 Å for GSGG substrate, 12.627 Å for PLD-BIG, and 12.633Å
for RIBS-BIG film.

High crystalline performance of fabricated BIG films results also in narrow linewidth of the ferromagnetic resonance
共FMR兲. FMR measurements were performed at room temperature by the broad-band spectrometer using the
H P8722D Network Analyzer simultaneously as a source
and a receiver of microwave signal. Figure 7 shows the typi-

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Adachi et al.

J. Appl. Phys., Vol. 88, No. 5, 1 September 2000

2737

FIG. 7. Ferromagnetic resonance 共FMR兲 absorption in PLD- and RIBSmade BIG共001兲 films measured at 9.25 GHz in magnetic field perpendicular
to the film.

FIG. 6. Same XRD patterns as in Fig. 5 for Bi3Fe5O12(0.128 ␮ m兲/
Gd3共ScGa兲5O12 structure fabricated by RIBS technique.

cal records of FMR differential absorption at 9.25 GHz in
PLD and RIBS films in magnetic field perpendicular to thefilm surface. The FMR linewidth at 9.25 GHz at room temperature in PLD and RIBS films in magnetic field perpendicular to the film surface was found to be ⌬H⫽25 and 34
Oe for PLD and RIBS film, respectively. The linewidth of
PLD-BIG is the narrowest in comparison with the results for
PLD-made BIG共111兲 reported earlier.7,8 The occurrence of
FMR in PLD-BIG in magnetic field is weaker than that in
RIBS. One displays lower magnetic anisotropy in PLD film
compared with RIBS-BIG. To quantify magnetic anisotropy,
the angular dependence of the resonance field has been measured 共see Fig. 8兲. The resonance field reaches the minimum
value in magnetic field parallel to the film plane, indicating
in-plane magnetic anisotropy in PLD- and RIBS-made
BIG共001兲 films. We have used the computational method,
similar to that proposed by Makino and Hidaka,11 to fit experimental polar angle dependence of the resonance field in
Fig. 8 by theoretical curve. Three fitting parameters, giving
the best fit to experimental data, were as follows the gyromagnetic ratio ␥ ⫽1.797⫻107 and 1.826⫻107 l/s Oe; the efTABLE II. Sample and detector positions used for 共4010兲 ␸ scans presented
in Figs. 5 and 6.
PLD
RIBS
共4010兲 Bragg␪ sample 共deg兲 2 ␪ detector 共deg兲 ␪ sample 共deg兲 2 ␪ detector 共deg兲
reflection
GSGG
BIG

63.17462.83082.59982.09963.23163.07882.52582.1614fective constant of uniaxial anisotropy K *u ⫽⫺8.66⫻10 and
4
3⫺8.60⫻10 erg/cm ; and the constant of cubic magnetic anisotropy K 1 ⫽⫺2.7⫻103 and ⫺3.8⫻103 erg/cm3 for PLD
and RIBS film correspondingly.
The magnetization M (H) in fabricated BIG films wasmeasured by vibrating sample magnetometer 关共VSM兲 Oxford
Instruments兴 whereas the Faraday rotation ␪ F (H) at 635 nm
was recorded in pulsed magnetic field 共raising time 2.7 ms,
maximum magnetic field 20 kOe兲. Figures 9 and 10 show
M (H 储 ) and M (H⬜ ) magnetization loops in parallel and perpendicular magnetic field, as well as Faraday rotation
␪ F (H⬜ ) hysteresis loops for PLD and RIBS BIG films. Para-

FIG. 8. Angular dependence of the ferromagnetic resonance 共FMR兲 fieldmeasured at 9.25 GHz. The polar angle ␪ is the angle between the external
magnetic field, rotating in the 共010兲 plane, and the normal to the film surface. The experimental data for PLD 共symbols 䊊兲 and RIBS 共symbols 䉭兲
BIG共001兲 films have been fitted to the theoretical curves, shown by solidlines, by variation of three fitting parameters: gyromagnetic ratio ␥, effective
constant of uniaxial anisotropy K *u , and the constant of cubic anisotropy
K 1 , presented in Table III.

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2738

Adachi et al.

J. Appl. Phys., Vol. 88, No. 5, 1 September 2000

TABLE III. Magnetic characteristics of Bi3Fe5O12 films fabricated by PLD
and RIBS techniques.

Magnetization 4 ␲ M s , Gs
Faraday rotation ␪ F , deg/␮m
Gyromagnetic ratio ␥, ⫻107 1/s•Oe
Effective constant of uniaxial anisotropy
43K*u , ⫻10 erg/cm
The constant of cubic anisotropy K 1 ,⫻103 erg/cm3
FMR linewidth @9.25 GHz and 300 K, Oe

FIG. 9. Pulsed laser deposited 0.73-␮m-thick Bi3Fe5O12 film. Magnetization
M vs H in magnetic field parallel H储 共symbols 䊉兲 and perpendicular H⬜
共symbols 䊊兲 to the film measured by vibrating sample magnetometer. Solidline shows Faraday rotation ␪ F vs H⬜ at 635 nm. Paramagnetic contribution
from Gd3共ScGa兲5O12 substrate has been subtracted.

magnetic contribution from GSGG substrate has been subtracted. The saturation magnetization 4 ␲ M s has been estimated to be about 1400 Gs for PLD film and 1200 Gs for
RIBS film.
In H储 geometry, magnetization saturates at rather low
magnetic field 共⭐600 Oe兲. In perpendicular magnetic field
H⬜ ,M -H⬜ curves saturate at higher fields ⭓1.6 kOe. We
have used the expression for the saturation magnetic field in‘‘hard’’ direction
H sat⫽

2 兩 K u* 兩Ms共2兲as an alternative to FMR tool to determine the effective constant of uniaxial anisotropy K *u . Substituting the experimen4
3
tal H sat data to Eq. 共2兲 we obtain 兩 K *u 兩 ⫽8.5⫻10 erg/cm for
4
3
PLD film and 8.2⫻10 erg/cm for RIBS film. With the experimental accuracy, higher for FMR and much lower for

PLD

RIBS

1400
⫺7.8
1.797
⫺8.66

1200
⫺6.9
1.826
⫺8.60

⫺2.7

⫺3.8

25

34

VSM measurements, the measured K u* constants coincidewith each other. Coercive force did not exceed 40 Oe forboth of the films. The saturated Faraday rotation of PLD filmshows ⫺7.8 deg/␮m and that of RIBS film is ⫺6.9 deg/␮m.
Taking into account the errors in the estimation of thickness
and volume of the films, it is suggested that both films show
almost the same magnetic and magneto-optical properties.
These results, presented in Table III, support the conclusionthat BIG films of high crystalline quality have been grownby PLD technique.
Recently we found the Faraday rotation of Cesubstituted YIG films made by PLD is remarkably dependent
on the oxygen pressure: ␪ F experienced change 2.2 times
when oxygen pressure has been varied from 10 to 100
mTorr.12 A similar effect was observed for PLD-BIG: film
performance is highly sensitivity to oxygen pressure in therange 5–200 mTorr. PLD-BIG共001兲 with superior crystalline
and magneto-optical performance has been prepared at 10
mTorr of O2.
In comparison with the results reported on RIBSBIG共111兲,1,2 the absolute values of saturation magnetization
and Faraday rotation obtained in this study for RIBSBIG共001兲 film were found to be smaller. At present, the exact origin of the difference in properties of 共111兲 and 共001兲
BIG films as well as the difference in 4 ␲ M s of PLD-madeand RIBS films are obscure, however, we have evaluated theperformance of both PLD and RIBS films grown onto thesame substrate, with the same size, using the same instruments. This is the most reliable way to make comparative
quality test and confirm PLD-BIG shows the performance
approaching the RIBS.
IV. CONCLUSIONS

FIG. 10. Same M – H and ␪ F-H hysteresis loops as in Fig. 8 for
Bi3Fe5O12(0.128 ␮ m兲/Gd3共ScGa兲5O12 structure fabricated by RIBS technique.

Completely
substituted
bismuthiron
garnet
Bi3Fe5O12共001兲 films have been successfully grown by KrF
pulsed laser deposition and reactive ion beam sputtering
techniques and film performance has been compared witheach other. PLD yields six times higher deposition rate thanthat of RIBS technique, which is of great advantage for industry application. The epitaxial quality of BIG films grownonto Gd3共ScGa兲5O12 substrate has been proven by comprehensive x-ray analyses. In-plane magnetization, low coercive
field ⭐40 Oe, low microwave loss 共FMR linewidth ⌬H⫽25 Oe@9.25 GHz兲, and high Faraday rotation of ⫺7.8
deg/␮m @635 nm make BIG/GSGG共001兲 thin film structures attractive for integrated magneto-optic applications.

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Adachi et al.

J. Appl. Phys., Vol. 88, No. 5, 1 September 2000

ACKNOWLEDGMENTS

The authors would like to thank Jesper Wittborn for his
help in thickness measurements by AFM and Huonju Kim
for useful discussions. This work was supported by the
Swedish Natural Sciences Research Council 共NFR兲 and Ministry of Education, Science, Sports, and Culture of Japan
共Monbusho兲.
1

T. Okuda, N. Koshizuka, K. Hayashi, K. Satoh, H. Taniguchi, and H.
Yamamoto, IEEE Trans. J. Magn. Jpn. 3, 483 共1988兲.
2
T. Okuda, T. Katayama, H. Kobayashi, and N. Kobayashi, J. Appl. Phys.
67, 4944 共1990兲.
3
A. Thavendrarajah, M. Pardavi-Horvath, P. E. Wigen, and M. Gomi, IEEE
Trans. Magn. 25, 4015 共1989兲.

2739

4

S. Mino, M. Matsuoka, A. Tate, A. Shibukawa, and K. Ono, Jpn. J. Appl.
Phys., Part 1 31, 1786 共1992兲.
5
Pulsed Laser Deposition of Thin Films, edited by D. B. Chrisey and G. K.
Hubler 共Wiley, New York, 1994兲, pp. 10–19.
6
D. Dijkkamp, T. Venkatesan, X. D. Wu, S. A. Shaheen, N. Jisrawi, Y. H.
MinLee, W. L. McLean, and M. Croft, Appl. Phys. Lett. 51, 619 共1987兲.
7
M. Y. Chern and J. S. Liaw, Jpn. J. Appl. Phys., Part 1 36, 1049 共1997兲.
8
N. Watanabe, N. Takahashi, and K. Tsushima, Mater. Chem. Phys. 54,
173 共1998兲.
9
T. Okuda, N. Koshizuka, K. Hayashi, T. Takahashi, H. Kotani, and H.
Yamamoto, IEEE Trans. J. Magn. MAG-23, 3491 共1988兲; Proc. Int.
Sympo. Magneto-Optics, J. Magn. Soc. Jpn. 11, Suppl. S1 179 共1988兲.
10
B. D. Cullity, Elements of X-Ray Diffraction 共Addison-Wesley, Reading,MA, 1988兲.
11
H. Makino and Y. Hidaka, Mater. Res. Bull. 16, 957 共1981兲.
12
H. Kim, A. M. Grishin, K. V. Rao, S. C. Yu, R. Sbiaa, and H. Le Gall,
IEEE Trans. Magn. 35, 3163 共1999兲.

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