Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering

Haoran He; Lixuan Tai; Di Wu; Hao Wu; Armin Razavi; Kin Wong; Yuxiang Liu; Kang L. Wang

doi:10.1063/5.0049044

Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering

Haoran He, Lixuan Tai, Di Wu, Hao Wu, Armin Razavi, Kin Wong, Yuxiang Liu, Kang L. Wang

College of Electrical Engineering and Computer Science

Research output: Contribution to journal › Article › peer-review

19 Citations (Scopus)

Abstract

Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)₂Te₃ (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (λ_IEE) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that λ_IEE is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin-orbit coupling between the BST and the CoFeB. Our work provides a method to enhance λ_IEE and is useful for the understanding of charge-to-spin conversion in TI-based systems.

Original language	English
Article number	071104
Journal	APL Materials
Volume	9
Issue number	7
DOIs	https://doi.org/10.1063/5.0049044
Publication status	Published - 2021 Jul 1

All Science Journal Classification (ASJC) codes

General Materials Science
General Engineering

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10.1063/5.0049044

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title = "Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering",

abstract = "Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)2Te3 (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (λIEE) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that λIEE is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin-orbit coupling between the BST and the CoFeB. Our work provides a method to enhance λIEE and is useful for the understanding of charge-to-spin conversion in TI-based systems.",

author = "Haoran He and Lixuan Tai and Di Wu and Hao Wu and Armin Razavi and Kin Wong and Yuxiang Liu and Wang, {Kang L.}",

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AU - He, Haoran

AU - Tai, Lixuan

AU - Wu, Di

AU - Wu, Hao

AU - Razavi, Armin

AU - Wong, Kin

AU - Liu, Yuxiang

AU - Wang, Kang L.

PY - 2021/7/1

Y1 - 2021/7/1

N2 - Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)2Te3 (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (λIEE) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that λIEE is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin-orbit coupling between the BST and the CoFeB. Our work provides a method to enhance λIEE and is useful for the understanding of charge-to-spin conversion in TI-based systems.

AB - Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)2Te3 (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (λIEE) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that λIEE is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin-orbit coupling between the BST and the CoFeB. Our work provides a method to enhance λIEE and is useful for the understanding of charge-to-spin conversion in TI-based systems.

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Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering

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