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Study of Giant Magnetoimpedance in Fe based ribbons

V. Satya Narayana Murthy1@, and G. Markandeyulu2

1Department of Physics, its Pilani ! "ydera#ad $ampus, "ydera#ad % &'''()2Department of Physics, **+ Madras, $hennai % '''-

Abstract

lectroma/netic nondestructi0e e0aluation ND methods ha0e #een 3idely used to find the

state and properties of the materials and also to determine the defects. +hese methods include

electric and ma/netic sensors or transducers such as eddy current, ma/netostricti0e,

electroma/netic acoustic transducers M4+, arkhausen sensors, /iant ma/netoresistance

GM5 sensors, ma/netoinducti0e sensors, etc. 6or instance, the eddy current method and the

residual ma/netic field techni7ue are often used to pre0ent the catastrophic fracture of

mechanical parts in machines. GM5 and ma/netoinducti0e sensors ha0e #een proposed fordetectin/ ma/netic fields created #y current passin/ throu/h conductors or locali8ed ma/netic

fields. +he lack of material continuity resultin/ from a crack produces a distur#ance in the

material9s ma/netic field, and the ma/nitude of this distur#ance is determined #y the si8e and

shape of the crack. Ma/netic field sensors re7uire a hi/h sensiti0ity to3ards the ma/netic field

are necessary to detect 0ery small fields created #y the defects in the material. Giant

Ma/netoimpedance GM* sensors are one such 3hich has hi/h sensiti0ity than GM5 or

ma/netoinducti0e sensors.

GM* is analo/ous to GM5. *n GM5 the resistance of the material chan/es in the presence of a

ma/netic field. *n the case of GM* it is the comple: impedance 3hich chan/es in the presenceof ma/netic field. +he main disad0anta/es of GM5 sensors are their lo3 sensiti0ity 2; < =e

and re7uirement of lar/e ma/netic fields. GM* sensors ha0e sensiti0ities of the order of 1''; =e ?1.

GM* is the chan/e in impedance of a soft ferroma/netic conductor in the presence of an e:ternal

ma/netic field.

GM* is defined as

ma:

ma:

2 2; 1''

2

=

Z H Z HZ

Z Z H

3here A" is the impedance at a field " and A"ma: is the impedance at a field at 3hich it

saturates.

+he GM* effect is useful for the de0elopment of field detectin/ sensors. 6or the de0elopment of

sensors a hi/h and sensiti0e GM* to3ards the applied ma/netic is re7uired. +he 0ariation of the

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GM* cur0e 3ith the applied ma/netic field should #e linear and the miniaturi8ation of the sensor

material is also an important parameter in the de0elopment of no0el ma/netic field sensors. 4

material 3ith hi/h and sensiti0e GM* can #e o#tained #y proper annealin/ treatments. +here are

0arious sensors that has #een de0eloped #ased on the GM* effect % current sensors, stress sensors,

#ioma/netic sensors, sensors for intelli/ent purpose such as fin/er print detection, car traffic

monitorin/ sensors, etc. +he GM* sensors are also useful in non destructi0e testin/ of materials

?2%C.

GM* is mainly o#ser0ed in 6e and $o #ased amorphous or nanocrystalline 3ires, ri##ons, thin

films, /lass coated 3ires, soft ma/netic tu#es, etc ?&%(. +he 6e and $o #ased alloys e:hi#it

hi/hly soft ma/netic properties compared 3ith the other alloys and intermetallic compounds. *n

the present study the 6e % #ased alloys 3ere prepared in an arc furnace in the presence of ar/on

atmosphere. 4morphous ri##ons of 1!2 mm 3idth and -'!C' mm thickness 3ere prepared

#y melt spinnin/ techni7ue in an ar/on atmosphere. +he impedance A, resistance 5 and

reactance measurements 3ere carried out usin/ "P C1E24 impedance analy8er on 1!& cmlon/ ri##ons in the fre7uency ran/e 1'' k"8!1- M"8 #y keepin/ the amplitude of the

alternatin/ current constant at 1' m4. 4 set of "elmholt8 coils 3as used to produce the

ma/netic field up to 1'' =e. +he ma/netic field sensiti0ities of the sensors 3ere calculated and

compared.

References

?1 F. Mohri, +. chiyama, H.P. Shen, $.M. $ai and H.V. Panina,J. Magn. Magn. Mater., 249

2''2 -&E

?2 5. "amia, $. $ordier, S. Sae8 and $. Dola#dIian, Sens. Lett., 72''E C-(

?- D. J. Fim, D. G. Park, and J. ". "on/ ,J. Appl. Phys. 912''2 (C21

?C J.M. arandiaran, G.V. Furlyandskaya, D.de $os, 4. GarcKa%4rri#as, and V. =. VasLko0skiy,

Sens. Lett., 72''E -(C

?& V. Satya Narayana Murthy and G. Markandeyulu, J. Magn. Magn. Mater. 312''( eE

? each 5. S. and 4. . erko3it8,J. Appl. Phys., 7! 1EEC 2'E

?( on/ Ahou, Jin7ian/ u, iaolin Ahao and in/chu $ai, IEEE. Trans. Magn., 3! 2'''

2E'

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