MAGNETIZATION REVERSAL MECHANISM IN CO-CR MEDIA FOR PERPENDICULAR MAGNETIC RECORDING

In this study Co-Cr thin films with perpendicular anisotropy are inves tigated. Three films with values for H-c of 11, 90 and 170 kA/m have b een selected for this paper. Besides the coercivity several other para meters such as the H-c/H-k, Cr-segregation, domain structure, column s izes, etc. were studied by VSM, SEM, NMR, MFM, AFM and selective etchi ng. The anomalous Hall effect (AHE) has been used to record the hyster esis curves of submicron Hall crosses, This very sensitive technique i n combination with e-beam lithography and ion-beam etching resulted in the recording of AHE hysteresis loops with dimensions of the Hall cro sses as small as 0.3 x 0.3 mu m(2). The AHE loops of three samples, wi th less than 60 columns, show different micromagnetic properties. Only the sample with H-c perpendicular to = 90 kA/m shows clear steps in t he curves above the noise level. The largest steps correspond with the reversal of one column and the total number of steps was five times t he number of columns for this sample. The different reversal mechanism s observed by the AHE are related to the differences in structure, coe rcivity and domain size.