Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electron Microscopy

Background:

• Electron Magnetic Circular Dichroism (EMCD) requires multiple angle-resolved electron energy loss spectra (EELS).
• Acquiring these spectra involves scanning the same sample area multiple times, which is prone to errors from beam damage, contamination, and drift.
• Precise spatial registration between scans is critical for accurate magnetic information.

Purpose of the Study:

• To develop a novel method for acquiring EELS data for EMCD in a single electron beam scan.
• To overcome the challenges associated with multiple scans in EMCD experiments.
• To enable more precise and reliable local magnetic measurements.

Main Methods:

• Utilized a custom-made quadruple aperture to collect four EELS spectra simultaneously.
• Performed EMCD analysis using data acquired in a single scan.
• Investigated quantitative EMCD results with sub-nanometer probe sizes and compared different detector geometries.

Main Results:

• Successfully acquired all necessary EELS spectra for EMCD analysis in a single electron beam scan.
• Eliminated complexities related to spatial registration and beam-induced sample modifications.
• Demonstrated quantitative EMCD results for a sub-nanometer probe size.

Conclusions:

• The custom quadruple aperture significantly simplifies EMCD experiments.
• This single-scan approach enhances the accuracy and reliability of local magnetic information.
• The method is applicable for advanced electron microscopy techniques requiring precise spectral acquisition.