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

APL Materials (Jul 2021)

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

Affiliations

Haoran He: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Lixuan Tai: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Di Wu: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Hao Wu: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Armin Razavi: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Kin Wong: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Yuxiang Liu: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
Kang L. Wang: Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA

DOI: https://doi.org/10.1063/5.0049044
Journal volume & issue: Vol. 9, no. 7
pp. 071104 – 071104-5

Abstract

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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.

Published in APL Materials

ISSN: 2166-532X (Online)
Publisher: AIP Publishing LLC
Country of publisher: United States
LCC subjects: Technology: Chemical technology: Biotechnology; Science: Physics
Website: http://aplmaterials.aip.org

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