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US 6,590,209 B1Granted
Technique to quantitatively measure magnetic properties of thin structures at <10 NM spatial resolution
AssigneeThe Regents of the University of California
InventorSasa Bajt
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Abstract
A highly sensitive and high resolution magnetic microscope images magnetic properties quantitatively. Imaging is done with a modified transmission electron microscope that allows imaging of the sample in a zero magnetic field. Two images from closely spaced planes, one in focus and one slightly out of focus, are sufficient to calculate the absolute values of the phase change imparted to the electrons, and hence obtain the magnetization vector field distribution.
Claims1
A method for quantitatively measuring the magnetization vector field of a magnetic structure, comprising:
- illuminating a magnetic structure with an electron wave;
- forming an electron image of said magnetic structure with said electron wave, wherein said electron image comprises pixels;
- measuring the intensity of said electron image;
- forming a defocused image of said electron image on either side of best focus;
- measuring the intensity of said defocused image;
- determining the difference between the intensity of said electron image and said defocused image to obtain the phase gradient;
- using the Nugent et al. transport-of-intensity equation, determining the phase of said magnetic structure quantitatively from said phase gradient;
- calculating the phase difference in the x-direction to obtain the magnetization vector in the x-direction;
- and
- calculating the phase difference in the y-direction to obtain the magnetization vector in the y-direction.
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Dependencies are inferred from the claim text.