Enhanced Spin-to-Charge Conversion Efficiency in Ultrathin Bi2Se3Observed by Spintronic Terahertz Spectroscopy

Hanbum Park; Kwangsik Jeong; In Hee Maeng; Kyung Ik Sim; Sachin Pathak; Jonghoon Kim; Seok Bo Hong; Taek Sun Jung; Chul Kang; Jae Hoon Kim; Jongill Hong; Mann Ho Cho

doi:10.1021/acsami.1c03168

Enhanced Spin-to-Charge Conversion Efficiency in Ultrathin Bi₂Se₃Observed by Spintronic Terahertz Spectroscopy

Hanbum Park, Kwangsik Jeong, In Hee Maeng, Kyung Ik Sim, Sachin Pathak, Jonghoon Kim, Seok Bo Hong, Taek Sun Jung, Chul Kang, Jae Hoon Kim, Jongill Hong, Mann Ho Cho

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

9 Citations (Scopus)

Abstract

Owing to their remarkable spin-charge conversion (SCC) efficiency, topological insulators (TIs) are the most attractive candidates for spin-orbit torque generators. The simple method of enhancing SCC efficiency is to reduce the thickness of TI films to minimize the trivial bulk contribution. However, when the thickness reaches the ultrathin regime, the SCC efficiency decreases owing to intersurface hybridization. To overcome these contrary effects, we induced dehybridization of the ultrathin TI film by breaking the inversion symmetry between surfaces. For the TI film grown on an oxygen-deficient transition-metal oxide, the unbonded transition-metal d-orbitals affected only the bottom surface, resulting in asymmetric surface band structures. Spintronic terahertz emission spectroscopy, an emerging tool for investigating the SCC characteristics, revealed that the resulting SCC efficiency in symmetry-broken ultrathin Bi2Se3 was enhanced by up to μ2.4 times.

Original language	English
Pages (from-to)	23153-23160
Number of pages	8
Journal	ACS Applied Materials and Interfaces
Volume	13
Issue number	19
DOIs	https://doi.org/10.1021/acsami.1c03168
Publication status	Published - 2021 May 19

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Government of Korea (MSIP) (No. 2018R1A2A1A05023214 and 2021M3H4A1A03052566).

Publisher Copyright:
© 2021 American Chemical Society.

All Science Journal Classification (ASJC) codes

Materials Science(all)

Access to Document

10.1021/acsami.1c03168

Cite this

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title = "Enhanced Spin-to-Charge Conversion Efficiency in Ultrathin Bi2Se3Observed by Spintronic Terahertz Spectroscopy",

abstract = "Owing to their remarkable spin-charge conversion (SCC) efficiency, topological insulators (TIs) are the most attractive candidates for spin-orbit torque generators. The simple method of enhancing SCC efficiency is to reduce the thickness of TI films to minimize the trivial bulk contribution. However, when the thickness reaches the ultrathin regime, the SCC efficiency decreases owing to intersurface hybridization. To overcome these contrary effects, we induced dehybridization of the ultrathin TI film by breaking the inversion symmetry between surfaces. For the TI film grown on an oxygen-deficient transition-metal oxide, the unbonded transition-metal d-orbitals affected only the bottom surface, resulting in asymmetric surface band structures. Spintronic terahertz emission spectroscopy, an emerging tool for investigating the SCC characteristics, revealed that the resulting SCC efficiency in symmetry-broken ultrathin Bi2Se3 was enhanced by up to μ2.4 times.",

author = "Hanbum Park and Kwangsik Jeong and Maeng, {In Hee} and Sim, {Kyung Ik} and Sachin Pathak and Jonghoon Kim and Hong, {Seok Bo} and Jung, {Taek Sun} and Chul Kang and Kim, {Jae Hoon} and Jongill Hong and Cho, {Mann Ho}",

note = "Funding Information: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Government of Korea (MSIP) (No. 2018R1A2A1A05023214 and 2021M3H4A1A03052566). Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",

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AU - Sim, Kyung Ik

AU - Pathak, Sachin

AU - Kim, Jonghoon

AU - Hong, Seok Bo

AU - Jung, Taek Sun

AU - Kang, Chul

AU - Kim, Jae Hoon

AU - Hong, Jongill

AU - Cho, Mann Ho

N1 - Funding Information: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Government of Korea (MSIP) (No. 2018R1A2A1A05023214 and 2021M3H4A1A03052566). Publisher Copyright: © 2021 American Chemical Society.

PY - 2021/5/19

Y1 - 2021/5/19

N2 - Owing to their remarkable spin-charge conversion (SCC) efficiency, topological insulators (TIs) are the most attractive candidates for spin-orbit torque generators. The simple method of enhancing SCC efficiency is to reduce the thickness of TI films to minimize the trivial bulk contribution. However, when the thickness reaches the ultrathin regime, the SCC efficiency decreases owing to intersurface hybridization. To overcome these contrary effects, we induced dehybridization of the ultrathin TI film by breaking the inversion symmetry between surfaces. For the TI film grown on an oxygen-deficient transition-metal oxide, the unbonded transition-metal d-orbitals affected only the bottom surface, resulting in asymmetric surface band structures. Spintronic terahertz emission spectroscopy, an emerging tool for investigating the SCC characteristics, revealed that the resulting SCC efficiency in symmetry-broken ultrathin Bi2Se3 was enhanced by up to μ2.4 times.

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