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Abstract The manipulation of magnetization through optically generated ultrafast spin currents is a fascinating area that needs a thorough understanding for its potential future applications. In this work, a comprehensive investigation of helicity‐driven optical spin‐orbit torque in heavy metal/ferromagnetic metal heterostructures is presented, specifically cobalt capped with gold or platinum, subject to laser pumping at different wavelengths. The results demonstrate up to tenfold enhancement in optical spin‐orbit torque quantum efficiency for gold compared to platinum of the same thickness when pumped with a visible laser. Additionally, the study provides the first experimental analysis of the photon energy dependence of optical spin‐orbit torque and derives the optical spin orientation spectra for both gold/cobalt and platinum/cobalt heterostructures. A key insight gained from the study is the impact of photon energy‐dependent spin transport in the system, which suggests the use of a high photon energy pump for efficient spin transport. These findings highlight the potential of spin current generation and manipulation in gold/ferromagnet heterostructures for a wide range of applications such as all‐optical magnetization switching, spin‐wave generation and control, and spintronic terahertz emission.
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A 3 pJ/bit free space optical interlink platform for self-powered tetherless sensing and opto-spintronic RF-to-optical transduction
Abstract Tetherless sensors have long been positioned to enable next generation applications in biomedical, environmental, and industrial sectors. The main challenge in enabling these advancements is the realization of a device that is compact, robust over time, and highly efficient. This paper presents a tetherless optical tag which utilizes optical energy harvesting to realize scalable self-powered devices. Unlike previous demonstrations of optically coupled sensor nodes, the device presented here amplifies signals and encodes data on the same optical beam that provides its power. This optical interrogation modality results in a highly efficient data link. These optical tags support data rates up to 10 Mb/s with an energy consumption of ~ 3 pJ/bit. As a proof-of-concept application, the optical tag is combined with a spintronic microwave detector based on a magnetic tunnel junction (MTJ). We used this hybrid opto-spintronic system to perform self-powered transduction of RF waves at 1 GHz to optical frequencies at ~ 200 THz, while carrying an audio signal across (see Supplementary Data for audio files).
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- Award ID(s):
- 1919109
- PAR ID:
- 10383542
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 11
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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