Electrostatic charging artefacts in Lorentz electron tomography of MFM tip stray fields

Using the technique of differential phase contrast (DPC) Lorentz electron microscopy, the magnetic stray field distribution from magnetic force microscopy (MFM) tips can be calculated in a plane in front of the tip using tomographic reconstruction techniques. Electrostatic charging of the tip during DPC imaging can significantly distort these field reconstructions. Using a simple point charge model, this paper illustrates the effect of electrostatic charging of the sample on the accuracy of tomographic field reconstructions. A procedure for separating electrostatic and magnetic effects is described, and is demonstrated using experimental tomographic data obtained from a modified MFM tip

Comparative study of the magnetic fields from MFM tips

No abstract available

Absolute field strength determination of magnetic force microscope tip stray fields

Quantitative analysis of magnetic force microscope (MFM) images is only possible if the magnetic state of the sensing tip is known. In this paper we describe a method which is used to characterise the stray field produced by an MFM tip. The method utilises Lorentz microscopy techniques and tomographic field reconstruction algorithms. A specially constructed calibration specimen enables measurement of the absolute values of the tip stray field to be made

Absolute field strength determination of magnetic force microscope tip stray fields

Quantitative analysis of magnetic force microscope (MFM) images is only possible if the magnetic state of the sensing tip is known. In this paper we describe a method which is used to characterise the stray field produced by an MFM tip. The method utilises Lorentz microscopy techniques and tomographic field reconstruction algorithms. A specially constructed calibration specimen enables measurement of the absolute values of the tip stray field to be made

AC LOSS IN AMORPHOUS GERMANIUM AT LOW TEMPERATURES

The frequency, temperature and field dependences of the audio frequency AC loss in a series of sputtered hydrogenated amorphous germanium samples are investigated over the temperature range 1 - 10K. The results conflict with the predictions of the model in which electrons are assumed to tunnel between localised states uniformly distributed in space and in energy

Quantitative field measurements from magnetic force microscope tips and comparison with point and extended charge models

In this article we present results and analysis from measurements of the field distributions from standard magnetic force microscope tips. These measurements are made using Lorentz microscopy and tomographic reconstruction techniques with the field reconstructed in a plane situated about 50 nm from the end of the magnetic force microscope (MFM) tip; this corresponds approximately to the sample plane in the MFM. By examination of the experimental results and comparison with simulated field distributions from point and extended charge distributions, we conclude that the magnetization configuration of the tip is best represented by an extended charge distribution and that the point pole approximation represents only, at best, the central part of the field distribution

OBTAINING ELECTRON ENERGY LOSS SPECTRA AND X-RAY EMISSION SPECTRA FREE OF INSTRUMENTAL ARTIFACTS

L'enregistrement des spectres EDX ou EELS est entaché d'erreurs dues à l'instrument. Si possible, celles-ci doivent être éliminées ; sinon, les spectres doivent être corrigés.When recording EDX and EELS spectra instrumental artifacts occur. If possible, they should be eliminated, if not the spectra should be corrected

Micromagnetics, microstructure and microscopy

Following a brief description of the deficiencies of a standard electron microscope for the study of magnetic microstructure, a description is given of a versatile TEM/STEM instrument designed to overcome these limitations. Preliminary results from a variety of imaging modes are presented and details are given of how coherent Foucault imaging can yield additional quantitative magnetic information not readily available using the other techniques