Magnetic imaging in the presence of an external field: erasure process of thin film recording medium

Abstract

The evolution of microscopic magnetic structures on a thin film recording medium has been imaged by applying a progressively increasing external magnetic field. Images from magnetic force microscopy with an in situ magnetic field revealed features attributable to probe-induced and sampleinduced effects. The probe effects result in the preferential sensitivity of the MFM imaging to the component of the local sample field in the direction of the probe's magnetization. The reorientation of the probe's magnetization with respect to the Sample plane direction causes the change in instrument response from detecting surface magnetic charges (magnetization divergence sensing) to detecting the surface magnetization distribution. Sample effects are more prominent at higher fields and the micromagnetic features of the recorded patterns follow a characteristic sequence as the unfavorably magnetized areas switch in the direction of the external f i e l d .

Magnetic Clusters in Molecular Beams, Metals, and Semiconductors

“…Although the ferromagnetic particles (-400 nm in diameter) produce strong magnetic force contrast, there exist particles (-50%) that show only weak contrast. The latter particles are likely to be ferromagnets with very low coercive fields and moment densities or possibly even superparamagnets at room temperature (33).…”

“…5B); in particular, the single-domain moments are observed to preferentially align along the three equivalent crystalline axes ((100), (010), (001)) of the GaAs host after the field is removed (31). The behavior of ferromagnetic particles can also be studied by continuous application of an in-plane field (33). For fields stronger than the tip coercive field (~400 Oe), the tip is forced to align with the in-plane field, thus allowing simple image interpretation.…”

Field-dependence of microscopic probes in magnetic force microscopy

“…Finally, the growing practice of MFM imaging in applied fields seeks to examine magnetic processes such as switching of submicron magnetic particles [8][9][10][11] and erasure of thin-film media. 12,13 The applied field can, however, affect both the tip and the sample, 8,12,13 and one must distinguish between these effects.…”

Effect of Trackwidth and Linear Spacing on Stability and Noise in Longitudinal and Perpendicular Recording

“…al. [3,4], This allowed uniform longitudinal or perpendicular fields to be applied to the disks while they were mounted on the microscope. Magnetic forces on the tip from the field coils as well as thermal constraints did not allow scanning during the application of the field.…”