Observation of ultrafast ballistic orbital transport
Date
2023-08-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Nature Nanotechnology
Abstract
Terahertz emission spectroscopy reveals long-distance ballistic orbital-angular-momentum transport in tungsten.
While most electronic devices so far are based on the electron’s charge or its spin degree of freedom, electrons can also carry orbital angular momentum. Orbitronics (orbital electronics), which focuses on the electron’s orbital angular momentum1, is much less explored than the field of spintronics, especially at terahertz (THz) frequencies2,3. However, orbitronics promises higher-density information transfer over longer distances in many materials than would be possible with spin currents. Furthermore, utilizing the electron’s orbital angular momentum L offers distinct advantages: (1) orbital current is an emergent property from Bloch states in a solid, comprising many atoms and, hence, orbital angular momentum transfer can be arbitrarily large1, whereas the spin angular momentum S of one electron is limited to 1/2h. This may hinder efficient transport and control of information in spintronic devices. (2) The conversion of orbital angular momentum to charge currents does not rely on spin–orbit coupling, suggesting that many more materials could potentially be harnessed for interfacing angular-momentum-based devices with charge-based devices4. Despite these advantages, it has been experimentally challenging to unambiguously distinguish L and S transport and their conversion into charge currents. Furthermore, it has been unclear if L transport could be used similarly to S transport at ultrafast timescales, potentially leading to efficient THz devices5,6.
Description
This article was originally published in Nature Nanotechnology. The version of record is available at: https://doi.org/10.1038/s41565-023-01458-4. This article will be embargoed until 02/07/2024.
Keywords
applied physics, condensed-matter physics
Citation
Jungfleisch, M.B. Observation of ultrafast ballistic orbital transport. Nat. Nanotechnol. 18, 1124–1125 (2023). https://doi.org/10.1038/s41565-023-01458-4