Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction

Area of Science:

• Materials Science
• Quantum Physics
• Electron Microscopy

Background:

• Aberration-corrected scanning transmission electron microscopy (STEM) is advancing to probe subatomic details.
• Measuring atomic electric fields using differential phase contrast (DPC) microscopy is challenging, traditionally relying on diffraction pattern shifts.

Purpose of the Study:

• To present a simplified quantum theoretical interpretation of DPC microscopy.
• To enable calculation of momentum transfer to the STEM probe from diffracted intensities.
• To quantify atomic electric fields, charge, and electron density.

Main Methods:

• Developed a simplified quantum theoretical interpretation of DPC.
• Utilized diffracted intensities recorded on a pixel array to calculate momentum transfer.
• Performed simulations for binary GaN and experimental studies on SrTiO3.

Main Results:

• Successfully quantified atomic electric fields in SrTiO3, validated by simulations.
• Achieved high-contrast imaging of light atoms.
• Demonstrated the capability to determine atomic electric fields, charge, and electron density.

Conclusions:

• The new interpretation and instrumentation upgrade enable STEM to quantify atomic electric fields.
• This advancement facilitates high-contrast imaging of light atoms.
• The method provides a pathway for detailed atomic-level characterization.