In microscopy, when are optical distortions actually useful? When controlled distortions—customized aberrations in scanning transmission electron microscopy (STEM)—can reveal magnetic behavior at the atomic level.
Working from a prediction that these customized aberrations could reveal magnetic behavior published in 2014, a team from the Oak Ridge National Laboratory designed an experiment to prove that this would work. The team (Juan Carlos Idrobo, Ján Rusz, Jakob Spiegelberg, Michael A. McGuire, Christopher T. Symons, Ranga Raju Vatsvai, Claudia Cantoni, and Andrew R. Lupini) recently published their findings in Advanced Structural and Chemical Imaging.
What Rusz et al. did was to use an aberrated electron probe to detect the ferromagnetic ordering of manganese in a compound of lanthanum, manganese, arsenic, and oxygen by observing a magnetic signal in the manganese-lanthanum edge.
The team believes that their results, while they prove the concept, can be improved going forward by straightforward improvements in the software that controls the probe, and with better spectrometers. These improvements could make it possible to study the magnetic ordering of individual atomic columns, and atomic size defects in materials. Applications could include, for example, smaller hard drives, and hard drives with larger storage capacities.
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