Quantum Insight: Advancing STEM-EELS for Materials Properties Detection

Scanning transmission electron microscopy (STEM), when combined with electron energy-loss spectroscopy (EELS), has the potential to detect properties associated with quantum materials with unprecedented spatial resolution. These properties include the emergence of magnetic ordering, valley polarization, phonon chirality, and topological characteristics such as Hall effects. In this study, we will show that achieving such measurements requires a configuration that ensures that electron momentum transfer in EELS mimics the role of polarization in light and X-rays.<br/><br/>Here, we will present three examples. [1] The first example demonstrates the detection of ferromagnetic ordering in lanthanum strontium manganite (LSMO) at room temperature. [2] The second example illustrates that orbital angular momentum, through the orbital Hall effect (OHE), can be detected and characterized at the nanometer scale. [3] The third example shows how EELS, though monochromation can be used to detect isotopic changes in oxygen in a Cr₂O₃ thin film, achieving atomic planes spatial resolution. [4]<br/><br/>[1] The EELS part of this research was supported by the Center for Nanophase Materials Sciences, which is a Department of Energy Office of Science User Facility. This research was conducted, in part, using instrumentation within ORNL’s Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. This work was also partly funded under the Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory, a multiprogram national laboratory operated by Battelle for the U.S. Department of Energy.<br/>[2] J.C. Idrobo et al. unpublished (2024).<br/>[3] J.C. Idrobo, et al. “Direct observation of nanometer-scale orbital angular momentum accumulation,” arXiv:2403.09269 (2024).<br/>[4] J.C. Idrobo et al. unpublished (2024).