High resolution magnetic force microscopy

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN022377 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Resonant torque magnetometry: a new in-situ technique for determining the magnetic properties of thin film MFM tips

A new high sensitivity Resonant Torque Magnetometry (RTM) technique has been developed enabling the determination of the magnetic properties of Magnetic Force Microscope (MFM) tips in-situ. A sensitivity of better than 10"' emu (lo-'' Am') has been achieved at ambient temperature and pressure. We have studied the micromagnetic properties of a variety of tip coatings including hard CoCr and Copt films and soft permalloy. In-situ determination of the magnetic properties of MFM tips is vital if quantitative interpretation of MFM images is to be achieved especially when images are made in the presence of bias fields. The m(p.,H) loops obtained for Copt tips have a shape similar to a standard magnetisation loop when the field is applied parallel to the tip axis. With the field applied perpendicular to the tip both Copt and CoCr demonstrate behaviour consistent with partial demagnetisation of the axial moment, to which the RTM is sensitive

Magnetic properties of electrodeposited nanowires

Electrodeposited multilayered nanowires grown within a polycarbonate membrane constitute a new medium in which giant magnetoresistance (GMR) perpendicular to the plane of the multilayers can be measured. These structures can exhibit a perpendicular GMR of at least 22% at ambient temperature. We performed detailed studies both of reversible magnetization and of irreversible remanent magnetization curves for CoNiCu/Cu/CoNiCu multilayered and CoNiCu pulse-deposited nanowire systems with Co:Ni ratios of 6:4 and 7:3 respectively in the range 10 - 290 K, allowing the magnetic phases of these structures to be identified. Shape anisotropy in the pulse-deposited nanowire and inter-layer coupling in the multilayered nanowire are shown to make important contributions to the magnetic properties. Dipolar-like interactions are found to predominate in both nanowire systems. Magnetic force microscope (MFM) images of individual multilayered nanowires exhibit a contrast consistent with there being a soft magnetization parallel to the layers. Switching of the magnetic layers in the multilayered structure into the direction of the MFM tip's stray field is observed

Characterisation of FeBSiC coated MFM tips using Lorentz electron tomography and MFM

Magnetic force microscope (MFM) tips coated with an amorphous ferromagnetic alloy have been studied using MFM and Lorentz electron microscopy. Imaging a standard NIST hard disk sample in the MFM reveals that the character of the tips varies dramatically with film thickness. The stray field distributions of the tips were determined using Lorentz electron tomography, and were found to be consistent with the contrast observed by MFM

Magnetic force microscopy of soft magnetic materials

The magnetic force microscopy of soft magnetic materials is a challenge due to the perturbing effect of the tip stray field on the samples magnetisation. Ferromagnetic thin film tips have been characterised by Lorentz electron microscopy and the tips employed in the study of a permalloy magneto-resistive sensor. Residual domains in the permalloy were detected and the location of domain walls related to the presence of imperfections in the edge of the sensor