Bir4Y2.6Fes0,2. Bi1.4Y16Tio, 1F84.9012. Y,Ga0.6F04.2012. La 0.03 Y 297Ga. Fe4.1012. La0.04 Y296 Gap.97Fe4.03012. Bi 4Y 1.6 Gap.i5Fe4.85012. 47.9.
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C o n v e r s i o ne l e c t r o n九t りs s b a u e rs p e c t r o s c o p i cs t u d y o fYIGs u b s t i t u t e dw i t hB i， T i， GaandLa K .Nomura8，T. Hanaia ，R .Sadamotoa ，Y .U j i h i r ab ，T .RyuoC and M.Tannoc a F a c u l t yofE n g i n e e r i n g，U n i v e r s i t yofTokyo，1 I 0ngo 7 3 1， Bunkyo・ku，Tokyo 1 1 3，Japan bR esearchCenterforAdvancedS c i e n c eandTechnology，U n i v e r s i t yo fTokyo， Komaba4 6・1，Meguro-ku，Tokyo1 5 3，Japan CA dvancedF u n c t i o n a lM a t e r i a l sResearchC e n t e r，S h i n E s t uChemicalC o .，L t d .， 1 s o b e2・1 3 1，A n n a k a c i t y，Gunma，Japan
YIGf i l m s，s u b s t i t u t e dw i t hB i，T i，Gaa n dL a，w c r cg r o w no na( 11 1 )p l a n co f r ) 5 0 1 2b yal i q u i dp h a s cc p i t a x i a lm c t h o d .W i t h出 G G d 3 G a 5 0 1 2o r( G d，Cah(Ga，Mg，Z i n c r c a s eo f出 ec o n c e n t r a t i o no fB ia t o m s，w h i c ha r es u b s t i t u t c da t2 4 cs i t c so fYIG， t h巴 m a g n c t i ch y p e r f i n ef i c l d sa t1 6 aa n d2 4 dF cs i t c si n c r e a s巴da n dt h cd i r c c t i o no f m a g n c t i cmomentsc h a n g e df r o mp a r al 1c lt o4 5t ot h巴(11 1 )p l a n巴. W i t ht h ei n c r e a s巴 o fGac o n c e n t r a t i o n，出巴 h y p c r f i n巴 f i e l d sa t1 6 aa n d2 4 dF es i t e sd e c r 巴a s c d .Theh y p c r f i n e i n t e r a c t i o na n dt h es u b s t i t u t i o ne f f c c to fYIGf i l m sa r巴 d i s c u s s c d 0
1 .
Introduction
Yttrium-iron-gamet(YIG)hasbeenused a samagnctic t h i nf i l m (-1μm) with magnetization perpendicular t ot h e plane f o r a magnetic bubble mcmory. Recently，i twasprovedt obeu s e f u la samagneto-opticali s o l a t o rbecausci tshows transparencyi nt h cneari n f r a r e dr e g i o nandapromincntFaradaye f f c c t[ 1 ] . YIG z[Dh012・Thc hasferrimagnetismandacubics t r u c t u r e，whichi sformeda s[Ch[A] u n i tc e l li scomposedofe i g h ts u b l a t t i c e s .[ C ]i o n sa r el o c a t c da tdodccahedral( 2 4 c ) s i t c s . [A] and [D] i o n s occupy o c t a h c d r a l( 16 a )s i t e s and t e r r a h e d r a l (24d) s i t e s， r e s p e c t i v c l y[ 2 ] .E s p e c i a l l y YIG c r y s t a l ss u b s t i t u t e d with diamagnetic Bi3 +i o n s showal a r g eFaradayr o t a t i o nof _104 deg/cm.TheCuriep o i n ti n c r e a s e switht h e ie .d T c / d [ B i J=3 8K.Thesedata i n c r e a s eoft h ec o n c e n t r a t i o nofBis u b s t i t u t e s[ B i ] .. wcrc cxp1ainedby t h emolecularf i e l dt h e o r yoft h r e e s u b 1 a t t i c e gamets [ 3 ] . YIG s i n g l ec r y s t a l scanbeuseda sam a g n e t o s t a t i cwavedcviccf o rt h et r a n s m i s s i o nof informationusingamicrowave.Themagnetizationcanbec o n t r o l l c dbyt h ea d d i t i o n ofGai o n s .Themagnetich y p c r f i n es t r u c t u r eandt h es u b s t i t u t i o ne f f e c tofYIGf i l m s o ramagneto-optical s u b s t i t u t c d withBi，Ti，Ga and La，which were devcloped f i s o l a t o randam a g n e t o s t a t i cwavedevice，werei n v c s t i g a t e dbyconversione 1 c c t r o n i f f r a c t o m c t r yandmagnetico b s e r v a t i o n s . Mossbauerspectroscopy(CEMS)，X-rayd
。c.BaltzerAG SciencePublishers J .
，
422
2 .
K .Nomurae ta. l/Con νe r s i o ne l e c t r o nMossbauers p e c t r o s c o p yofYIG
Experimentald e t a i l s
i t hB i，Ga，T iandLa，weregrownona( 11 1 )p l a n eof YIGf i l m s，dopedw 012(GGG)o r(Gd，Cah( Ga，Mg，Z r ) S O I 2byal i q u i dphasee p i t a x i a lmethod Gd3GaS (LPE)i nab a t hofPbOandB2 03[ 2 ] .Ti-dopedBiYIGwasp r e p a r e da sano p t i c a l i s o l a t o r .Ga-dopedYIGf i l m swerep r e p a r e df o ram a g n e t o s t a t i cwaved e v i c e .The t h i c k n e s s e soft h ep r e p a r c df i l m swerea b o u ts e v e r a Itcnsμm.TheYIGf i l m swere coveredw i t hat h i ncarbonf i Im ( 10-20nmt h i c k )i no r d e rt oa v o i dt h ee l e c t r i f i c a t i o n I esduringt h emeasurementofc o n v e r s i o ne l e c t r o nMossbauer e f f e c tofi n s u l a t o rsamp (CEM)s p e c t r au s i n gab a c k s c a t t e r i n gt y p eg a sflowc o u n t e r[ 4 ] .TheCEMs p e c t r a werer e s o l v e di n t otwos e x t e t sofL o r e n t z i a n，c o r r e s p o n d i n gt o1 6 aand24dFes i t e s， bycomputer日t t i n g . 3 .
R e s u l t sandd i s c u s s i o n
3 .1 .
BiYIGFORA MAGNETO-OPTICALISOLATOR
CEM s p e c t r a ofB ixY3_>)G (x= 0，0 . 2， 1 .2 and 1 .4 ) wcre measured. The Mossbauerp a r a m e t e r so b t a i n c dfromt h c s cs p e c t r aandI a t t i c ec o n s t a n t sa r eshown i nt a b l e1 .Witht h ei n c r e a s coft h ec o n c e n t r a t i o nofB is u b s t i t u t e sa t24cs i t e sof h eI a t t i c ec o n s t a n ti n c r e a s e d and t h emagnctich y p e r f i n ef i e l d s t h eYIGc r y s t a I，t )andH i n ( d )，i n c r e a s e daI it t l c .H i n ( a )andH i n ( d )f o r b o t ha t1 6 aand24ds i t e s，H川a B i1 .4Y 1 .6 IG were 5 0 . 3T and 41 .7T，r e s p e c t i v e l y . The H i n ( a )r e a c h e ds a t u r a t i o n f a s t e rt h a nH i n ( d ) .H i n ( a )andH i n ( d )f o ras p u t t e r e de p i t a x i a If i Im ofB i3Fes 012were r e p o r t e dt obc4 9 . 8T and4 2 . 7T，r e s p e c t i v e l y[ 3 ] .Thei n t e n s i t yr a t i oofmagnetic peaksa t2and5t opeaks1and6d e c r e a s c dfrom 1 .1t o0 . 5 6a t1 6 as i t e sandfrom 1 .3t o0 . 5 5a t24ds i t e s，r e s p e c t i v e l y .Thisi n d i c a t e st h a tt h enumberofmagnetic momentsp e r p e n d i c u l a rt ot h c( 1 1 1 )s u r f a c ei n c r e a s e di nBi-dopedYIGf i Ims，whereas h es u r f a c e .By t h eundopedYIGc o n t a i n e da l m o s ta I Imagneticmomentsp a r a I I e Itot dopingw i t hal a r g eamountofB i，t h es p i n swereo r i e n t e di nt h ed i r c c t i o nof450， ona v e r a g e，w i t hr e s p e c tt ot h e( 111 )p l a n e . Theisomers h i f tf o ri r o na t1 6 as i t e s，I S ( a )，i n c r e a s e dw i t ht h edopingofB i a l t h o u g hI S ( d )f o r24d s i t e sd i d not .T his s u p p o r t sI o c a l i z e d molecularo r b i t a I t h e o r y[ 5 ] .Dopingw i t has m a I IamountofB ip r o v i d e dt h enarrowI i n e w i d t h sa t16a s i t e s .T h e r e f o r e，t h eMossbauerp a r a m e t e r sofFe3+ i o n sa t1 6 as i t e swerea f f e c t e d more出 a nt h o s ea t24ds i t e s .Theq u a d r u p o l es p l i t t i n g(QS)wasa th i g h e s t0 . 0 9mm/s a t1 6 as i t e sand0 . 1 2mm/sa t24ds i t e sf o rh i g h l yBi-dopedspecimens，r e s p e c t i v e l y . TheQSwasv e r ys m a I Ibccauset h eo v e r a I Is t r u c t u r eofYIGf i Imswaskeptc u b i c . Thepeaka r e ar a t i oof1 6 at o24dFe3+ i o n swasl e s st h a n0 . 5 7，whichwasIower t h a nt h eo c c u p a t i o nr a t i oof0 . 6 6f o rani d e a Is t r u c t u r eofYIG.T h i smaybecaused rPb2 +f romt h em e l tofPbOandB2 03 [ 6 ] . byt h ei n c o r p o r a t i o nofy3+ o 1 日c i e n tofTi-dopedB i1 .4 Y2 . t785nm Thea b s o r p t i o nc o e f 6IGwas73cm- a m a I I e rcomparedw i t h 160cm-1 ofBiYIG.Ont h e wavelength，whichwasmuchs
血T )，i s o m e rs h i f t s( lS，mm/s)，q u a d r u p o l es p l i t t i n g(QS，mm/s)，l i n e w i d t h s(W，mm/s)，i n t e n s i t yr a t i oo fm a g n e t i cp e a k s H y p e r f i n ef i e l d s(H， (PR=P P1 .6) ，a r e ar a t i o( l6 a/ 2 4 d )o ft h eo c t a h e d r a l( a )a n dt e t r a h e d r a l( d )s u b l a t t i c e s，andl a t t i c ec o n s t a n t(A)o fYIGf i l m s . . 2 S/
F i l m s
H i n ( a ) H皿 ( d )
I S ( a ) I S ( d ) QS(a) QS(d) W(a) W(d)
PR(a) PR(d)
1 6 a / 2 4 d
L a t t i c eC
0. 42 0 . 5 6
1 .06
1 . 20
0 . 5 3
1 2 . 3 7 4 4
0 . 0 1
0 . 3 5 0 . 5 4
1 .06
1 . 30
0. 53
1 2 . 3 8 0 2
0 . 0 2 -0 . 0 3
0 . 3 3 0 . 5 6
0 . 4 6
0 . 5 9
0 . 5 4
1 2. 494
41 .7
0. 41 0 . 1 8 -0.09 -0.12
0 . 4 3 0 . 6 3
0 . 5 6
0 . 5 5
0 . 5 7
1 2 . 4 9 7 2
4 9 . 3
41 .2
0 . 3 9 0 . 1 4 -0 . 0 8 -0 . 1 1
47 0 0. . 6 4
0 . 3 6
0 . 3 7
0 . 6 4
1 2 . 5 0 2
Ga o . 6 F e4.401 Y3 2
45. 4
37. 4
0 . 3 2 0 . 1 5
0 . 0 4
0 . 0 1
0 . 5 4 0 . 6 2
1 . 17
1 . 33
0 . 5 9
1 2 . 3 6 9 8
41 .0
3 5 . 0
0. 4
0 . 0 6
0 . 0 1
1 . 1
1 . 2
1 . 3
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3664 1 2.
8 .
L a o . aY2 .9 7Ga o . 9F e 4 . 1 01 2 L a o 倒Y2.96Gao.97Fe4ω01 2
4 0 . 7
3 4 . 6
0 . 3 5 0 . 1 5
0 . 0 7 -0 . 0 1
1 .00 1 .0 3
1 .00
1 . 33
0. 43
1 2 . 3 6 5 0
9 .
G a o . 1 SF巴4 B i1 . 4 Y1 .6 . 8 501 2
49. 4
41 .2
0 . 3 7 0 . 1 7
0 . 0 3
0 . 4 4 0 . 5 8
0 . 3 5
0 . 2 5
0 . 5 9
1 2. 4956
YIG
4 7 . 9
3 8 . 7
0 . 3 2 0 . 1 6
2 .
es OI2 Bも2Y2 . 8F
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3 9 . 7
0 . 3 6 0 . 1 5 -0.02
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B i1.2Y1 .8 Fes 012
49. 5
.2 41
0 . 3 7 0 . 1 7
4 .
eS01 .4YI .6F 2 B il
5 0 . 3
5 .
.4 Y1 .6 B i1 T i o . 1F e 4 . 9 0 1 2
6 . 7 .
0 . 1
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0 . 0 4
1 .0
﹄円・宅。ョ宅bRa ・¥門リ。ミ刊号。=丘町内向、。=ミ A u a E E向、起町内向、28 ミミ﹃日
T a b l e1
品N 凶
424
K .Nomurae tal ./C o n v e r s i o ne l e c t r o nMδ' s s b a u e rs p e c t r o s c o p y0 1YIG
( a )
(ぺ戸}口口、内﹄司﹂﹂}A'H司︺町川戸口200
Velocity (mm/s) .CEMspec町 aof( a )Y I G .( b )Bil .4 YI .6 Fe5U12・ F i g .1 and( c )Bil . 4 YI .6 T i o .Fe4.9U'2・
，
o t h e rhand，t h eFaradayr o t a t i o nc o n s t a n t sf o rT i・dopedB iI .4 Y 2 . 6 I Ga n dBiYIGwere -8.85X 1 03deg / cmand -9.02x1 03deg/cm，r e s p e c t i v e l y .ThedopingofTip r o v i d e d 3 t h ee x c e l l e n timprovemento ft r a n s p a r e n c y .I ti sc o n s i d e r e dt h a tdopedT i +p r e v e n t s Fe3+ fromchangingi n t oFe4 +d uet ot h ei n c o r p o r a t i o no fPb2 + . CEMs p e c t r ao f YIG，B iI .4Y I .6 1GandTi-dopcdB iI .S1 . 6I Gf i l m sa r eshowni nf i g .1 .TheHi fTino 1yandt h enumberofs p i n so r i e n t e dp e r p e n d i c u l a rt o dopedBiYIGd e c r e a s e ds l i g ht t h e( 111 )p l a n ei n c r e a s c dw i t hr e s p e c tt oB iI .4Y I .6 I G . The peak r a t i oo f1 6 a t o 24d i r o ns i t e s became c l o s et ot h ei d e a lo c c u p a t i o nr a t i o .T i3+ i o n smight 2 p r e v e n t y3+ o rPb+ from i n c o r p o r a t i n gi n t o1 6 as i t e s，i na d d i t i o nt o ac h a r g e compensatione f f c ct .
K .Nomurae ta l ./C o n v e r s i o ne l e c l r o nMossbauerS p e C l r o s c o p y0 1YIG
3 . 2 .
425
Ga-DOPEDYIGFORMAGNETO-STATICWAVEDEVICE
I nh i g h l yGa-dopedYIGf i l m s .La3+ i o n swerea l s odopedi n24cY s i t e si n o r d e rt oa v o i dt h es e r i o u sd e c r e a s eoft h el a t t i c ec o n s t a n toft h ee p i t a x i a lf i l m s .The changeoft h el a t t i c ec o n s t a n to ft h e s eGa-dopedYIGf i l m swasw i t h i n0 . 0 1λWith t h ei n c r e a s eofdopeddiamagneticGa3+. b o t hH i n ( a )andHin(d)d e c r e a s e dandt h e l i n e w i d t h sbecameb r o a d .Thi si sdue10t h eweakeningo fsuper-exchangei n t e r a c t i o n a t16aa n d / o r24ds i t e s .Th es p i no r i e n t a t i o nofa l 1Ga-dopedYIGwasp a r al 1e lt o t h e( 111 )p l a n e .Thespectrumofh i g h l yGa-dopcdYIGc o u l dn o tbef i t t e d weI l enought od i s c u s st h es i t ep o p u l a t i o nof16aand24dp r e c i s e l y .Theh y p e r f i n ef i e l d s a r ep l o t t e da g a i n s tm a g n e t i z a t i o noft h e s eYIGc r y s t a l si nf i g .2 .OnGa-doping.t h e
1 6 a
日
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/寸 r i r-g
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3 0
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4πMs(G)
F i g .2 .H y p e r f i n ef i e l d sa n ds a l u r a l i o nm a g n e l i z a l i o no fG a d o p e dYIG
s a t u r a t i o nm a g n e t i z a t i o nofYIG d e c r e a s e d more d r a s t i c a l Iy . from 1800t o 320G i n ( a )= 4 7 . 9TandHin(d)= 3 8 . 7Tt oH i n ( a )= 40T comparedw i t hHin.changingfromH and Hin(d)= 34T. r e s p e c t i v e l y . The s a t u r a t i o n magnetization of LaGaYIG. 4πMs= 365G. was a p p r o x i m a t e l yi n d c p e n d e n t oft e m p e r a t u r e . The t e m p e r a t u r e dependencewasa b o u t50ppm; oC a t5 . 5GHz.whichc o r r e s p o n d st o1 / 4 0oft h a tof YIG.I ti sknownt h a tt h ep e r p c n d i c u l a rr e s o n a n c ef i e l ddependsont h es a t u r a t i o n m a g n e t i z a t i o nandt h ea n i s o t r o p i cf i e l d .Th eGa-dopcdBiYIG.B i1 .4 YI .6 G a O . 1 S F e 4 . 8 S 0 1 2 . p r e p a r e di no r d e rt oa d j u s tt h es a t u r a t i o nm a g n e t i z a t i o n( 4 π Ms= 1550G)t ot h e a n i s o t r o p i cf i e l d (Hk= 1550O e ) . showed a s t a b l e pc中 c n d i c u l a rr e s o n a n c ef i e l d i nt h et e m p e r a t u r er a n g eof-60t o80o C .TheH i n ( a )andH i n ( d )d c c r e a s e ds I ig h t l y . n d i c u l a rt ot h e( 11 1 )p l a n ei n c r e a s e dbyt h e andt h enumberofs p i n so r i e n t e dpe中 e dopingofGa.
426
4 .
K .Nomurae la l .! C o n v e r s i o ne l e c l r o nMδs s b a u e rs p e c l r o s c o p yo fYIG
C o n c l u s i o n s
I twaso b s e r v e dt h a tw i t ht h ei n c r c a s eoft h ec o n c e n t r a t i o nofB iatomsdoped i n t o24cs i t e sofYIG.t h em a g n e t i ch y p e r f i n ef i e l d sofFe3+ i o n sa t1 6 aand24d s i t e si n c r e a s e da n dt h eI So fFe3+i o n sa t1 6 as i t e si n c r e a s e d .Thcser e s u l t ss u g g e s t e d oFe3+ a t1 6 as i t e sr a t h e rt h a na t24ds i t e s . t h a te l e c t r o n sa r et r a n s f e r r e dfrom02-t Thepeaka r e ar a t i oof1 6 aa n d24ds i t e swass m a l lcomparedw i t ht h a toft h ei d e a l s t r u c t u r e .Byt h edopingofB ii n t oY s i t e s，t h emagnetics p i n swereo r i e n t e dfrom 11 1 )p l a n et o450，whereast h es p i n swerek e p tp a r a l l e lt ot h e( 11 1 ) p a r a l l e lt ot h e( p l a n ebyt h edopingo fGai o n si n t oFes i t e s .Thechangei nh y p e r f i n ef i e l d swas s m a l lcomparedw i t ht h ed r a s t i cd e c r e a s eofs a t u r a t i o nm a g n e t i z a t i o nbyt h edoping ofG a .Ti-dopedBiYIGa n dGa-dopedBiYIGshowede x c e l l e n tc h a r a c t e r i s t i c sof a no p t i c a li s o l a t o ra n dam a g n c t o s t a t i cwave，r c s p c c t i v e l y .CEMSi su s e f u lf o rt h e a n a l y s i sofYIGf i l m sgrownc p i t a x i a l l yonat h i c ks u b s t r a t e . R e f e r e n c e s ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 )
P. J .P i c o n ea n dA . H .M o r r i s h .1 .App l .P h y s .5 3( 19 8 2 ) 2 4 71 . T .H i b i y a .OyoB u t u r i5 5( 19 8 6 ) 1 0 9 . .B o t t y釦.I .S .S z u c s，P . E .Wigen釦 dM.Gomi.H y p .I n t .54( 19 9 0 ) 6 3 9 M.P a r d a v i H o r v a t h，L K .Nomuraa n dY .U j i h i r a .B u n s e k iKagaku3 3( 19 84)T81 . F. J .K a h n .P . S .P e r s h a na n dJ . P .R e e i k a，P h y s .R e v .1 8 6( 19 6 9 ) 8 9 1 t o h .K .S a n e y o s h i .T .Toriyamaa n dK .H i s a t a k e .J .App. lP h y s .60( 19 8 6 ) 1 4 61 . J .I
