Conversion of charge to orbital angular momentum through the orbital Hall effect (OHE) holds transformative potential for the development of orbital-based electronics, however, it is challenging to directly observe the electrically generated orbital accumulation. Here, we detect the OHE by directly quantifying the orbital accumulation along the edges of a titanium thin film using a scanning transmission electron microscope. We measure the Ti L-edge using electron energy-loss spectroscopy with nanometer resolution and find a sizable orbital accumulation at the sample's outer perimeters, consistent with all signatures expected for the OHE, and determine an orbital diffusion length ℓo≈7.3 nm. Our data points to a surprising dependence of the orbital diffusion length on the nano-structural morphology.
@article{arxiv.2403.09269,
title = {Direct observation of nanometer-scale orbital angular momentum accumulation},
author = {Juan Carlos Idrobo and Ján Rusz and Gopal Datt and Daegeun Jo and Sanaz Alikhah and David Muradas and Ulrich Noumbe and M. Venkata Kamalakar and Peter M. Oppeneer},
journal= {arXiv preprint arXiv:2403.09269},
year = {2024}
}