2938 IEEE TRANSACTIONS ON MAGNETICS, VOL. MAG-17, NO. zyxw 6, NOVEMBER 1981 AN INVESTIGATION zyxwvutsrq OF THE MAGNETIZATION DISTRIBUTION AND MAGNETIZATION PROCESSES IN SYMMETRICAL 90’ NIFE CHEVRON ELEMENTS Alan J. Collins and Mazen Husni Abstract - A high magnification Kerr magneto-optic microscope and ferrofluid techniques have been used t o investiqate the maqnetization distributions and domain patterns in 90’ chevron elements, under rotating applied field conditions. Considerable magnetic interaction has been observed to exist between themagnetization levels in the orthogonal legs of the chevrons. The magnitude of the interaction effects are dependent upon the orientation of the applied field relative to the legs of the chevron. INTRODUCTION Evidence that the magnetization distribution in one 1 eg of a 900 chevronelement i s influenced by the state of magnetization in the perpendicular leg has been reported by Krinchik 11 [ , In that investigation a field was applied parallel to one leg, which was sufficient to saturate the centre of the leg, and the magnetization distribution was measured in the per- pendicular leg. In the present work the interaction effects that exist between thelegsofunconnected 900 chevron elements have been further investigated by measuring the magnetization distribution for various applied field orientations and observinqcorresponding domain configurations. Themagnetization distributions havebeen measured in chevrons(thelegdimensionsof which were 16 um x zyxwvutsr 3 pm x 0.45 urn) using a highmagnification magneto- optic microscopeincorporating a motor driven sample stage and a versatile electronic detection andaverag- ing system 121 . The spacing between the individual chevrons was 3 vm and no interaction was observed between adjacentchevrons. THE MAGNETIZATION DISTRIBUTION IN 90’ CHEVRONS Observations of the domain patternsinchevrons, usingferrofluidtechniques, have revealedtheexist- ence of complex closure domain structures, similar to those shown in Fig. la. These domain structures have been observed in zero applied fields or when t h e f i e l d was applied in a fixed direction. For similar applied fieldconditions,magneto-optic measurements by the authors 131 and Huijer zyxwvutsr 141 have also revealed the existence of complex domain structures. However, measurements on a large number of chevronsinthe Presentinvestigation,has shown t h a t these complex domain structures do not exist under rotating field conditions. Thus under these conditions, the measured approach to saturation and the magnetization distri- butionsinchevrons,are found t o be continuous with no abruptchanges. The magnetizationdistributionsMx(x), when t h e rotating field is parallel to onelegofthechevron, withthefieldamplitude Hx as a parameter, is shown in Manuscript received 18th March , 1981. Alan 3. Collins and Mazen Husni are with the Wolfson Centre for Magnetics Technology, 30 The Parade, Cardiff, Wales, UK. Fig. 2. The distributions are not symmetrical about the centre of the leg as they are about the centre of an I bar 13 1 . The asymmetry in the magnetization levelsinchevrons is also evident in the observed domain patterns, Fig. lb. The domain configuration also reveals that there exists an interaction between themagnetizationwithineachleg,asthe domain walls in the leg perpendicular to the applied field are dis- placedinsuch a manner that a netmagnetization M (y) exists along the leg. Y zy x-l Fig. 1 Domain p a t t e r n s in 90’ chevrons 1.M) 0.75 - zyxwvuts 0.50 0.25 Error bar +’ 0.00 I x3 x2 x (rm) X1 Fig. 2 The magnetization distributions. Mx(x), along leg A of a 90’ chevmn elemnt. for various applied vaiues, HX. parallei to leg A. Fig. 3 shows themagnetizationdistributions Mx(x) withinoneleg of a chevron when the rotating field, having a magnitude of 40 Oe, was p a r a l l e l , per- pendicular and at 45’ to leg A, curves 1, zyx 2 and 3 respectively. Curve 2 illustrates again the interaction which exists between themagnetizationwithineachleg, as in this case there is no ’ a p p l i e d field’ parallel to the leg. The magnetizationdistributionforfieldsat 450, can be explained by resolving the field into two components parallel and perpendicular to the leg. These two field components give rise to magnetization distributions of the form shown incurves 1 and 2, from which curve 3, themagnetization distribution for fields applied a t 450, can be qualitatively deduced. 0018-9464/81/1100-2938$00.75 0 1981 IEEE