Orbital Hall effect-driven spin-orbit torque enhancement in Ti-based systems via rare-earth interface engineering

Fuente: arXiv
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Main Authors: Mondal, Rohiteswar, Raghu, Chennoju, Baral, Animesh, Haldar, Arabinda, Murapaka, Chandrasekhar
Format: Preprint
Published: 2026
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author Mondal, Rohiteswar
Raghu, Chennoju
Baral, Animesh
Haldar, Arabinda
Murapaka, Chandrasekhar
author_facet Mondal, Rohiteswar
Raghu, Chennoju
Baral, Animesh
Haldar, Arabinda
Murapaka, Chandrasekhar
contents Orbital currents in light metals offer large orbital Hall conductivities, yet translating this into practical spin-orbit torque efficiency is hindered by fundamental limitations. In this work, we introduce a Gd interlayer between a Ti orbital source and a Co ferromagnet to enhance the orbital torque efficiency. Ferromagnetic resonance-based spin (orbital) pumping measurements identify an optimal Gd thickness of around 4 nm, where the orbital-to-spin conversion efficiency reaches its maximum. The Ti-thickness dependence of the inverse orbital Hall effect signal confirms a bulk orbital Hall origin in Ti and yields a qualitative orbital diffusion length exceeding 20 nm. Spin-torque ferromagnetic resonance measurements demonstrate a fivefold enhancement of the SOT efficiency in Ti(20 nm)/Co compared to a Gd(4 nm)/Co reference. Interestingly, the trilayer Ti/Gd/Co architecture exhibits a spin (orbital) torque efficiency greater than 1, which is higher than that of the bilayer Ti/Co and Gd/Co structures, irrespective of Ti thickness. These results establish rare-earth interlayer engineering as a viable route to enhanced orbital torque efficiency for next-generation spin-orbitronic devices.
format Preprint
id arxiv_https___arxiv_org_abs_2606_01308
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Orbital Hall effect-driven spin-orbit torque enhancement in Ti-based systems via rare-earth interface engineering
Mondal, Rohiteswar
Raghu, Chennoju
Baral, Animesh
Haldar, Arabinda
Murapaka, Chandrasekhar
Materials Science
Orbital currents in light metals offer large orbital Hall conductivities, yet translating this into practical spin-orbit torque efficiency is hindered by fundamental limitations. In this work, we introduce a Gd interlayer between a Ti orbital source and a Co ferromagnet to enhance the orbital torque efficiency. Ferromagnetic resonance-based spin (orbital) pumping measurements identify an optimal Gd thickness of around 4 nm, where the orbital-to-spin conversion efficiency reaches its maximum. The Ti-thickness dependence of the inverse orbital Hall effect signal confirms a bulk orbital Hall origin in Ti and yields a qualitative orbital diffusion length exceeding 20 nm. Spin-torque ferromagnetic resonance measurements demonstrate a fivefold enhancement of the SOT efficiency in Ti(20 nm)/Co compared to a Gd(4 nm)/Co reference. Interestingly, the trilayer Ti/Gd/Co architecture exhibits a spin (orbital) torque efficiency greater than 1, which is higher than that of the bilayer Ti/Co and Gd/Co structures, irrespective of Ti thickness. These results establish rare-earth interlayer engineering as a viable route to enhanced orbital torque efficiency for next-generation spin-orbitronic devices.
title Orbital Hall effect-driven spin-orbit torque enhancement in Ti-based systems via rare-earth interface engineering
topic Materials Science
url https://arxiv.org/abs/2606.01308