Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 25: Magnetic Imaging

MA 25.4: Vortrag

Mittwoch, 18. März 2015, 10:15–10:30, H 1012

Quantification of microscopic magnetic and/or electric fields by calibrated DPC measurements — •Felix Schwarzhuber, Johannes Wild, Ralph Schregle, and Josef Zweck — Institute of Experimental and Applied Physics, University of Regensburg

Differential phase contrast microscopy (DPC) in a scanning transmission electron microscope (STEM) allows to obtain detailed information about microscopic electric and/or magnetic field distributions within a specimen. The deflection of the electron beam due to those fields leads to a shift of the diffraction disk in the detector plane, which can be detected using a direction sensitive detector.

In order to retrieve quantitative information about those electric and/or magnetic fields a calibration of the beam deflection as a function of field strength is necessary. We present a simple calibration method which is based on the defined deflection of the convergent electron beam after passing the electric field of a parallel-plate capacitor that is built in a TEM holder. The diffraction disk shift caused by a well known capacitor field at a certain set of microscope parameters allows to derive device specific calibration factors. With this calibrated DPC system it is possible to quantitatively measure fields that cause deflections in the order of microradians.