INHOMOGENEOUS MAGNETIZATION IN AMORPHOUS Ni-Fe BASED ALLOYS

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INHOMOGENEOUS MAGNETIZATION IN AMORPHOUS Ni-Fe BASED ALLOYS

Jodi Schneider, A. Handstein, I. Henke, K. Závěta, T. Mydlarz

To cite this version:

Jodi Schneider, A. Handstein, I. Henke, K. Závěta, T. Mydlarz. INHOMOGENEOUS MAGNETI- ZATION IN AMORPHOUS Ni-Fe BASED ALLOYS. Journal de Physique Colloques, 1980, 41 (C8), pp.C8-682-C8-685. �10.1051/jphyscol:19808171�. �jpa-00220273�

JOURNAL DE PHYSIQUE Colloque C8, suppldrnent au n08, Tome 4 1 , aoct 1980, page C8-682

INHOMOGENEOUS PIAGNETIZATION I N AMORPHOUS N i - F e BASED ALLOYS J. Schneider, A. Handstein, I. Henke, K. ~ ~ v g t a * and T. Mydlarz ^2%

ZWF, AdW der DDR, 8027 Dresden, Postfach, DDR

*Inst. o f Phys., Czechosl. Acad. Sci., 280 40 Prague 8, CSSR

" ~ n t e r n . Lab. for High Magn. Fields and Low Temp., hrroclaw, Poland.

I n t r o d u c t i o n

I n t h e amorphous N i - r i c h ( FexKil-x) s o P l o ~ i t l l o y s , t h e m a g n e t i z a t i o n M( T,H) a p p e a r s t o be h e t e r o g e n e o u s up t o t h e c r i t i c a l c o n c e n t r a t i o n [l]

.

I n t h e p r e s e n t work, we r e p o r t on measu- r e m e n t s of M ( T , H ) i n h i g h magnetic f i e l d s up t o 1 4 T a s w e l l a s on t h e r e s u l t s of s m a l l a n g l e X-ray s c a t t e r i n g e x p e r i m e n t s .

E x p e r i m e n t a l

Samples of t h e same nominal c h e m i c a l com- p o s i t i o n were p r e p a r e d by t h e T a y l o r t e c h n i q u e i n t h e form of t h i n w i r e s and a s r i b b o n s by t h e c o n v e n t i o n a l s i n g l e - r o l l e r t y p e quenching. A l l t h e s a m p l e s u s e d f o r t h e s u b s e q u e n t measurements were c a r e f u l l y checked by X-ray d i f f r a c t i o n t o be amorphous.

The M ( T , H ) c u r v e s were measured by a b a l - l i s t i c method i n t h e t e m p e r a t u r e r e g i o n f r o m l i q u i d iie up t o 200 K. F o r t h e s m a l l a n g l e X-ray s c a t t e r i n g e x p e r i m e n t s a t room t e m p e r a t u r e a h o r i z o n t a l d i f f r a c t o - m e t e r and monochromatic C o - r a d i a t i o n were u s e d .

R e s u l t s and U i s c u s s i o n

The i n v e s t i g a t e d s a m p l e s w i t h 0 . 0 4 ~ ~ ~ 0 . 2 show a r e m a r k a b l e n o n l i n e a r i n c r e a s e o f t h e m a g n e t i z a t i o n up t o t h e h i g h e s t f i e l d u s e d . T y p i c a l

2

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19808171

2 4 6 8 10 12

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Fig.1. Arrott-Belov-Kouvel p l o t s f o r F i g . 2 . A r r o t t - B e l o v - h o u v e l p l o t s f o r ( F e O , 1N i 0 . 9 ) 8 0 ~ 1 0 ~ 1 0 w i r e s i n (Fe0.07Ni0,93 )80p10B10 r i b b o n s

h i g h f i e l d s i n f i e l d s up t o 1 4 T

The i n t e n s i t y d i s t r i b u t i o n i n t h e s m a l l a n g l e X-ray s c a t t e r i n g e x p e r i m e n t s f o r x=0.07 a s a f u n c t i o n of t h e s c a t t e r i n g a n g l e i s g i v e n i n F i g . 3 . C o r r e c t i o n s f o r t h e normal background and a d d i t i o n a l s c a t t e r i n g were a p p l i e d t o t h e d a t a . The i n t e n s i t y a t low s c a t t e r i n g a n g l e s i n - c r e a s e s upon a n n e a l i n g . Assuming " c h e m i c a l p a r t i c l e s " w i t h a mean d i a m e t d r of

a b o u t 200 % and no i n t e r f e r e n c e e f f e c t s , a r - e a s o n a b l e f i t t o t h e o b s e r v e d i n t e n s i - t y c u r v e i n t h e as-quenched s t a t e was

o b t a i n e d . The d i f f e r e n c e s between t h e t h e o r e t i c a l c u r v e and t h e e x p e r i m e n t a l p o i n t s may be due t o a d i s t r i b u t i o n i n p a r t i c l e s i z e . T h i s r e s u l t s u p p o r t s o u r e a r l i e r a s s u m p t i o n [l] t h a t t h e e x i s t i n g c o m p o s i t i o n a l f l u c t u a t i o n s o r phase p r e - c i p i t a t e s r e s u l t i n inhomogeneous magne- t i z a t i o n and c o n s e q u e n t l y i n n o n - l i n e a r ABK p l o t s .

S m a l l - a n g l e s c a t t e r i n g e x p e r i m e n t s i n a l - l o y s w i t h x=0.5 show no f o r m a t i o n o f c h e - m i c a l c l u s t e r s o f t h e s i z e o f 1 0 0 9 o r

JOURNAL DE PHYSIQUE

rt h

0 annealed sample

O 1 3 0 0 O C , lh)

O -oso\l

O 0 0 0 O 0°-m3

Fig.3. S m a l l - a n g l e X-ray i n t e n s i t y v s s c a t t e r i n g a n g l e :

o e x p e r i m e n t a l p o i n t s

-

l a r g e r . T h i s i s e x p e c t e d from t h e e x p e r i - m e n t a l l y d e t e r m i n e d magnetic p h a s e d i a - gram f o r (FexNil-x )80P10B10 fd] , a c c o r d i n g t o which t h e c o m p o s i t i o n s w i t h x > 0 . 2 2 a r e m a g n e t i c a l l y homqgeneous.

The r e c i p r o c a l d i f f e r e n t i a l s u s c e p t i b i l i - t y ti,^) = ( ~ , M ( H , T ) / ~ I - I ) - ~ a s a f u n c t i o n of H i s g i v e n i n F i g . 4 f o r x=0.1. I t I S

s e e n t h a t f o r some r a n g e of f i e l d s and t e m p e r a t u r e s t h e dependence of may be a p p r o x i m a t e d a s b e i n g l i n e a r i n H; t h e s l o p e d e c r e a s e s w i t h i n c r e a s i n g tempera- t u r e . S i m i l a r b e h a v i o u r was a l s o found f o r x=0.04 and 0.07. T h i s h i g h f i e l d de- pendence of # c a n n o t be e x p l a i n e d by t h e normal law of a p p r o a c h of m a g n e t i z a t i o n t o s a t u r a t i o n . F o r t h e p a r a p r o c e s s r e s u l t - i n g from t h e t h e r m a l l y e x c i t e d magnons one f i n d s t h e r e l a t i o n y * l I - l i 2 ~ 5 1 ; a t e r m of t h i s form was i n f a c t o b s e r v e d i n mag- n e t i c a l l y homogeneous system[6J. Compared

t o t h i s c a s e , o u r m a g n e t i c a l l y inhomoge- n e o u s s y s t e m d i s p l a y s a n anomalous c o n t r i - b u t i o n t o t h e p a r a p r o c e s s which may o r i - g i n a t e f r o m t h e i n f l u e n c e of t h e e x t e r n a l

Eig.4. R e c i p r o c a l d i f f e r e n t i a l s u s c e p - t i b i l i t y v s H f o r

(Fe0.1Ni0.9)80Y10B10

f i e l d on s u p e r p a r a m a g n e t i c c l u s t e r s p r e - s e n t i n t h e f e r r o m a g n e t i c m a t r i x [2,3].

Such a phenomenological model a l s o e x p l a i n s t h e o b s e r v k d c u r v e d A r r o t t - Belov-Kouvel p l o t s [2,3,7].

The a u t h o r s g r a t e f u l l y acknowledge t h e p o s s i b i l i t y of u s i n g t h e h i g h f i e l d f a - c i l i t i e s of t h e I n t e r n a t i o n a l L a b o r a t o r y o f Iiigh Magnetic F i e l d s and Low Tempera- t u r e s in Wroclaw, Poland.

R e f e r e n c e s

[d

.,

[2] J . S c h n e i d e r e t a l . , p h y s . s t a t . s o 1 . a 56( 19791K141

-

[j] X.Zbv6ta e t a l . , Proc. Srd Conf. on R a p i d l y Quenched M e t a l s , B r i g h t o n

( 1 9 7 8 ) p.156

[q

Roy.Soc. =(1968)127 [5] T . H o l s t e i n and H.Primakoff, Phys.Rev.

[6] H. K r onmiiller and H . G r i m m , J

.

Magn.Mat. 2 ( 1 9 7 7 ) 5 7

[q

.

Mat. g ( 1 9 7 9 ) 5 8