DocumentCode :
788959
Title :
The effect of a hard axis bias field on the switching field in single layer and bi-layer thin permalloy films
Author :
Farrell, G.P. ; Hill, E.W.
Author_Institution :
Dept. of Eng., Manchester Univ., UK
Volume :
31
Issue :
6
fYear :
1995
fDate :
11/1/1995 12:00:00 AM
Firstpage :
4041
Lastpage :
4043
Abstract :
A sensitive method for the measurement of individual Barkhausen events has been developed which enables the reconstruction of hysteresis loops to be performed with great accuracy. The examination of such loops reveals that for Bloch wall transitions a hard axis bias field, Hb , has little effect until Hb>0.5 Hk. At this point, the Bloch walls give way to Neel type transitions, which are energetically more favourable. There is a decrease in the field required to cause nucleation and the loop narrows. A model of the Neel wall energy shows a linear decrease in energy as a bias field is applied. In this case, the wall energy is proportional to the field required to cause rotation in the plane of the material, and thus a linear decrease in switching field with bias field is also observed. Where Neel walls provide the rotation mechanism the loop is also observed to shear towards the saturation direction, causing a decrease in the permeability of the material. This is thought to be due to an increase in the wall stiffness, i.e. a reluctance for the magnetisation in the centre of the walls to rotate away from the bias field direction
Keywords :
Barkhausen effect; Neel temperature; Permalloy; ferromagnetic materials; magnetic domain walls; magnetic hysteresis; magnetic permeability; magnetic switching; nucleation; Bloch wall transitions; Fe-Ni; Neel type transitions; Neel wall energy; bi-layer thin permalloy films; hard axis bias field; hysteresis loops; individual Barkhausen events; magnetisation; nucleation; rotation mechanism; saturation direction; single layer thin permalloy films; switching field; wall stiffness; Coils; Electric variables measurement; Frequency; Magnetic field measurement; Magnetic hysteresis; Magnetization reversal; Mathematical model; Performance evaluation; Signal generators; Switches;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/20.489855
Filename :
489855
Link To Document :
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