THE INFLUENCE OF THE PERPENDICULAR ANISOTROPY ON THE CURRENT INDUCED RESONANCE FIELD SHIFT IN (Fe0.3Ni0.7)78Si8B14 AMORPHOUS RIBBON

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THE INFLUENCE OF THE PERPENDICULAR ANISOTROPY ON THE CURRENT INDUCED RESONANCE FIELD SHIFT IN (Fe0.3Ni0.7)78Si8B14

AMORPHOUS RIBBON

A. Wadas

To cite this version:

A. Wadas. THE INFLUENCE OF THE PERPENDICULAR ANISOTROPY ON THE CURRENT

INDUCED RESONANCE FIELD SHIFT IN (Fe0.3Ni0.7)78Si8B14 AMORPHOUS RIBBON. Journal

de Physique Colloques, 1985, 46 (C6), pp.C6-409-C6-412. �10.1051/jphyscol:1985677�. �jpa-00224932�

JOURNAL DE PHYSIQUE

Colloque C6, supplkrnent au n09, Tome 46, septernbre 1985 page C6-409

THE INFLUENCE OF THE PERPENDICULAR ANISOTROPY ON THE CURRENT INDUCED RESONANCE FIELD S H I F T I N ( ~ e ~ . j N i O . 7)78SigB14 AMORPHOUS RIBBON

A . Wadas

I n s t i t u t e o f P h y s i c s PAN, aZ. Lotnikdw 32/46, 02-668 Warsaw, Poland

Resum6 - C e t t e note concerne l e s v a r i a t i o n s d e champ de r6sonance i n d u i t e s par un courant continu. L1influence d ' u n r e c u i t , e t l a modification a s s o c i 6 e du champ d l a n i s o t r o p i e - eff e c t i f %(4iTM), sur l e ddplacement du champ d e resonance

i n d u i t par un c o u r a n t , sont dbcr it s. Le ddplacement du champ de resonance augment e l o r sque 1 'anisotropic e f f e c t i v e d6croTt.

A b s t r a c t - T h i s n o t e c o n c e r n s t h e changes of t h e resonance f i e l d caused by dc c u r r e n t . The i n f l u e n c e of a n n e a l i n g and t h e change of t h e e f f e c t i v e a n i s o t r o p y 4nM - ^H connected w i t h it on t h e c u r r e n t induced resonance f i e l d s h i r t i s reported.The resonance f i e l d s h i f t i n c r e a s e s t o g e t h e r w i t h t h e d e c r e a s e of t h e e f f e c t i v e a n i s o t r o p y .

I - INTRODUCTION

The i n f l u e n c e o f d c c u r r e n t on such magnetic p r o p e r t i e s a s domain s t r u c t u r e , p e r m e a b i l i t y , m a g n e t i s a t i o n and resonance f i e l d h a s been r e p o r t e d i n d e t a i l s by s e v e r a l authors/l-6/. The mentioned e a r l i e r p a p e r s have concerned t h e magnetic p r o p e r t i e s of amorphous r i b b o n s . The change of t h e resonance f i e l d d e s c r i b e d i n /3-6/ w i l l be d i s c u s s e d a l s o i n t h i s n o t e . So, we w i l l p r e s e n t some c o n c l u s i o n s o b t a i n e d i n t h e e a r l i e r works t h a t a r e e s s e n t i a l and worth t o be r e p e a t e d .

The resonance f i e l d s h i f t induced by dc c u r r e n t h a s been observed i n some of amorphous r i b b o n s l i k e : Fe-Ni-Si-B, Co-Ni-Si-B, Fe-Si-B.

I f we r o t a t e t h e sample i n t h e p l a n e p e r p e n d i c u l a r t o t h e c u r r e n t d i r e c t i o n we c a n o b s e r v e t h e change of s i g n of t h e r e s o a a n c e ' f i e l d s h i f t i n Fe-Ni-Si-B, Co-Ni-Si-B a l l o y s . The l a r g e s t s h i f t is observed when t h e magnetic r e s o n a n c e f i e l d i s p e r p e n d i c u l a r t o t h e r i b b o n p l a n e . The resonance f i e l d s h i f t s t o t h e lower v a l u e s i n t h i s c o n f i g u r a t i o n . When t h e r e s o n a n c e f i e l d i s p a r a l l e l t o t h e r i b b o n p l a n e t h i s s h i f t

i s s m a l l e r and t h e r e s o n a n c e f i e l d s h i f t s t o t h e h i g h e r v a l u e . W e can deduce t h a t t h i s s h i f t i s c o r r e l a t e d by t h e change of t h e e f f e c t i v e p e r p e n d i c u l a r a n i s o t r o p y . This change may be connected w i t h t h e r e s i - d u a l domain s t r u c t u r e d i f f e r e n t i n d i f f e r e n t r i b b o n composition.

The h i g h e r resonance f i e l d s h i f t c o r r e s p o n d s t o t h e induced s t r a i n s t a t e i n t h e t e c h n o l o g i c a l process/6/. The mechanical p o l i s h i n g and t h e a n n e a l i n g a f t e r it i l l u s t r a t e s u s t h i s dependence. By t h e method p r e s e n t e d e a r l i e r /6/ we can s e e t h a t up t o t h e c e r t a i n v a l u e of t h e c u r r e n t i n t e n s i t y J t h e resonance f i e l d s h i f t induced by t h e c u r r e n t i s l i n e a r l y dependent on t h e magnetic f i e l d H . The problem how t h e resonance f i e l d s h i f t depends on t h e e f f e c t i v g a n i s o t r o p y ^{? I 8} which h a s been mentioned o n l y i n t h e l a s t work w i l l be t h e aim of t h e p r e s e n t work.

I1 - EXPERIMENT

The (Fe 3Ni.7)78Si8B14 amorphous ribbon h a s been t a k e n t o t h e e x p e r i - ment.

The C u r i e t e m p e r a t u r e - ^Tc=1800C

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985677

C6-4 10 JOURNAL DE _PHYSIQUE

The ribbon was 30 t h i c k , 1 mm wide and 3 nun long. The dc c u r r e n t was a p p l i e d p a r a l c l t o t h e long a x i s of t h e ribbon. The ferromagne- t i c resonance has been observed a t 9.36 GHz. The resonance f i e l d s h i f t has been measured a t c u r r e n t i n t e n s i t y up t o t h e 0.08 A. Furthermore, t h i s s h i f t was measured only a t two p o s i t i o n s of t h e sample when magnetic resonance f i e l d i s p a r a l l e l o r p e r p e n d i c u l a r t o t h e ribbon

plane. The resonance f i e l d s h i f t h a s been marked A H A ( 0') and ~ ~ ~ ( 9 0 ' ) r e s p e c t i v e l y . The s u b s c r i p t "I" t e l l s u s t h a t t h e c u r r e n t d i r e c t i o n i s

always p e r p e n d i c u l a r t o t h e resonance f i e l d d i r e c t i o n . The experimen- t a l arrangement i s shown i n t h e fig.1.

F i g i l Schematic r e p r e s e n t a t i o n of t h e experimental arrangement.

The amorphous ribbon considered i n t h i s work was annealed a t d i f f e r e n t temperatures up t o 174OC ( a i r atmosphere 1, 40 minutes a t each one and t h e n slowly cooled t o room temperature where t h e measurements have been done. A f t e r each such a s t e p t h e e f f e c t i v e a n i s o t r o p y was calcu- l a t e d . Fig.2 p r e s e n t s t h e p l o t s of t h e measured s h i f t a ~ ~ ( 9 0 ~ ) and c a l c u l a t e d e f f e c t i v e a n i s o t r o p y 4rM - ^HU vs. annealing temperature.

Fig.2 Dependence of t h e resonance f i e l d s h i f t g H L ( 9 0 0 ) and i v e a n i s o t r o p y on t h e a n n e a l i n g temperature.

t h e e f f e c t -

The e f f e c t i v e a n i s o t r o p y 4KM - ^H.- h a s been c a l c u l a t e d from two w e l l known resonance e q u a t i o n s ; ^U

o0 (w/a)2= ur ^(H,

^4TM - H,)

Values of ~ ~ ~ ( 9 0 " ) a r e p r e s e n t e d a t t h r e e d i f f e r e n t c u r r e n t i n t e n s i t i - e s i - e ; 0.04 A, 0.06 A, 0.08 A. The e x p e r i m e n t a l e r r o r was a b o u t % 3G.

The r e s u l t s p o i n t o u t t h a t t h e d e c r e a s e of t h e e f f e c t i v e a n i s o t r o p y r e l a t e s t o t h e i n c r e a s e of t h e b ~ ~ ( 9 0 " ) . S i m i l a r l y t h e resonance f i e l d s h i f t o H L ( O O ) behavioues f o r t h e same a n n e a l i n g t e m p e r a t u r e s .

The s h i f t s d ~ ~ ( 9 0 O ) and a H ~ ( 0 " ) a r e n o t l i n e a r v s . c u r r e n t i n t e n s i t y a s i t was r e p o r t e d e a r l i e r /3/. Using t h e v a l u e s of H ( g o 0 ) and H ( 0 " ) we can c a l c u l a t e t h e e f f e c t i v e a n i s o t r o p y 4XM - ^H . ~ f ~ u r e 3 p r e s & n t s t h i s dependence and t h i s i s t h e answer on t h e q u e g t i o n i n c l u d e d i n t h e I n t r o d u c t i o n .

Fig.3 Dependence o f t h e resonance f i e l d s h i f t a H 1 ( 9 0 ° ) on t h e e f f e c t - i v e a n i s o t r o p y 4XM - ^HU a t d e f i n i t e d v a l u e s of t h e a n n e a l i n g tempera- t u r e s .

AHJ.(~o") depends l i n e a r l y on t h e e f f e c t i v e a n i s o t r o p y up t o t h e 130°C

( c r i t i c a l p o i n t of t h e m a t e r i a l s t a b i l i t y ) . The c o e f f i c i e n t of l i n e -

a r i t y depends on t h e c u r r e n t i n t e n s i t y , t h e n it becomes h i g h e r a t

h i g h e r c u r r e n t i n t e n s i t y ( n o t l i n e a r l y ) . W e can o b s e r v e t h e change

of s t r a i n i n such a manner. We assumed e a r l i e r /5/ t h a t t h e change

of r e s i d u a l domain s t r u c t u r e ( induced by d c c u r r e n t ) c a u s e s t h e

resonance l i n e s h i f t . W e can c o n n e c t t h i s s p e c i f i c domain s t r u c t u r e

w i t h t h e p e r p e n d i c u l a r a n i s o t r o p y . The microwave t e c h n i q u e r e f l e c t s

t h e magnetic s t a t e a t a l a y e r n e a r t h e r i b b o n s u r f a c e (low p e n e t r a t i o n

d e p t h 1. So, t h e r e s i d u a l domains which d e s c r i b e t h e p e r p e n d i c u l a r

a n i s o t r o p y by t h e i r p o s i t i o n a r e v e r y u n s t a b l e and v e r y s u s c e p t i b l e

on a t r a n s v e r s e magnetic f i e l d . But t h e r e o r i e n t a t i o n of t h e r e s i d u a l

domain i s l i m i t e d by t h e l a r g e resonance magnetic f i e l d .

JOURNAL DE PHYSIQUE

I I1 - CONCLUS IONS

The main r e s u l t o b t a i n e d i n t h e c o n s i d e r e d measureinents i s t h e l i n e a r dependence of t h e r e s o n a n c e l i n e s h i f t induced by d c c u r r e n t v s . t h e e f f e c t i v e a n i s o t r o p y 4JTN - ^H . The measurement of t h e resonance magnetic f i e l d s h i f t inducedUby dc c u r r e n t may be t h e method a l l o w i n g t o c o n t r o l t h e change of t h e e f f e c t i v e a n i s o t r o p y d u r i n g t h e a n n e a l i n g p r o c e s s . Furthermore, p a s s i n g dc c u r r e n t i s a s i m p l e way t o reduce t h e e f f e c t i v e a n i s o t r o p y and it i s conducted i n t h e l i n e a r manner.

REFERENCES

/1/ Aroca, C . , Lopez, E . and Sanchez, P .S., J.Magn .Magn .Mat. 23 (1 981) 193 /2/ B u t t i n o , G. , c e c c h e t t i , A., Poppi,M. and ~ i n i , G., ~ . ~ a ~ n . E g n . ~ a t . 41

(1984) 205

/3/ Wadas, A., J.Magn.Magn.Mat. 46 ( 1 984) 102

/4/ Wadas,A., 2nd 1nt.Conf. on P h y s i c s of Magn.Mat. J a d w i s i n , 1 4 3 (1984) Poland

/5/ Wadas, A., J.Magn.Magn.Mat. 49 (1985) 150

/6/ Wadas, A., J.Magn.Magn.Mat. i n p r e s s