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Orbital current has attracted significant attention in recent years due to its potential for energy-efficient magnetization control without the need for materials with strong spin–orbit coupling. However, the fundamental mechanisms governing orbital transport remain elusive. In this study, we systematically explore orbital transport in Ti/Ni bilayers through orbital pumping, drawing an analogy to spin pumping. The orbital current is generated and injected into the Ti layer via the microwave-driven orbital dynamics in Ni, facilitated by its strong spin–orbit correlation. We employed thickness-dependent ferromagnetic resonance measurements and angular-dependent inverse orbital Hall effect (IOHE) detection to probe orbital transport in Ti based on the conventional spin-pumping methodology. The observed enhancement in the damping factor indicates an orbital-diffusion length of ∼5.3 ± 3.7 nm, while IOHE-based estimation suggests a value of around 4.0 ± 1.2 nm, which confirms its short orbital-diffusion length. Furthermore, oblique Hanle measurements in the longitudinal configuration reveal an orbital relaxation time of approximately 16 ps. Our results establish that orbital pumping, analogous to the conventional spin-pumping framework, can serve as a robust technique for elucidating orbital transport mechanisms, paving the way for the design of efficient spin-orbitronic devices.
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This content will become publicly available on December 29, 2026
Efficient spin transport across a disordered interface in a low damping magnetic insulator/heavy metal bilayer
We demonstrate efficient spin transfer across a disordered interfacial layer that forms in low damping ferrimagnetic insulator lithium aluminum ferrite (LAFO) and tantalum bilayers. Despite the interfacial disorder, confirmed by transmission electron microscopy, we find a room temperature interfacial spin mixing conductance on the order of 1014 Ω−1m−2 similar to other LAFO-based bilayers with epitaxial interfaces. Broadband ferromagnetic resonance measurements confirm a linewidth broadening in LAFO following the addition of a Ta layer, consistent with the effects of spin pumping. Furthermore, the presence of spin current generated in the Ta layer by spin pumping is confirmed with inverse spin Hall effect measurements. Measurements of the Ta thickness dependence of the spin Hall magnetoresistance and the Gilbert damping enhancement indicate that the Ta spin diffusion length is on the order of 1 nm. This work not only provides a surprising example of efficient spin transport across a disordered interface but also demonstrates the potential for low damping spinel ferrites as a robust system for efficient spin wave spintronics.
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- Award ID(s):
- 2105114
- PAR ID:
- 10656754
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 127
- Issue:
- 26
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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