Magnetisation reversal mechanism in Co-Cr media for perpendicular magnetic recording

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

[发布日期] 1997-04-01

[关键词] Co-Cr;reversal mechanism;thin film;Hall effect;micromagnetism