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Quantitative magnetic mapping in TEM through accurate 2D thickness determination
Joseph Vimal Vas1, Hasan Ali2, Wen Shi1
1Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich, 52425, Germany.
Ultramicroscopy
|May 17, 2025
Summary
Accurate thickness measurements using Electron Energy Loss Spectroscopy (EELS) are crucial for quantitative magnetic mapping with Transmission Electron Microscopy (TEM). This study presents a method to precisely determine the inelastic mean free path (λ) for improved EELS accuracy.
Area of Science:
- Materials Science
- Physics
- Electron Microscopy
Background:
- Off-axis Electron Holography and Electron Magnetic Circular Dichroism (EMCD) offer high spatial resolution magnetic mapping.
- Current limitations in quantitative magnetic measurements stem from imprecise sample thickness determination.
- Electron Energy Loss Spectroscopy (EELS) is a promising technique for thickness mapping, but requires accurate inelastic mean free path (λ) estimation.
Purpose of the Study:
- To develop a straightforward approach for precisely determining the inelastic mean free path (λ).
- To enable accurate thickness measurements using EELS for quantitative magnetic analysis.
- To compare EELS-derived thickness measurements with established methods like Convergent Beam Electron Diffraction (CBED) and Scanning Electron Microscopy (SEM).
Main Methods:
- Determining the inelastic mean free path (λ) for accurate EELS-based thickness measurements.
- Acquiring EELS maps to assess spatial thickness variations.
- Comparing EELS thickness data with CBED and SEM measurements, especially for thin samples (<100nm).
- Applying calibrated thickness measurements to TEM-based magnetic mapping techniques.
Main Results:
- A straightforward method for precise inelastic mean free path (λ) determination was established.
- Accurate thickness maps were generated using EELS.
- Discrepancies were observed between EELS and CBED/SEM thickness measurements, particularly in samples thinner than 100nm.
- Quantitative magnetic maps were successfully obtained by integrating calibrated EELS thickness data.
Conclusions:
- Precise determination of the inelastic mean free path (λ) significantly enhances the quantitative capabilities of EELS for thickness measurements.
- Accurate thickness mapping using EELS is essential for improving the quantification of magnetic information obtained from advanced Transmission Electron Microscopy (TEM) techniques.
- The developed method provides a pathway to more reliable quantitative magnetic imaging in materials science.
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