# Enhanced spin–orbit torque efficiency via interface engineering in BiSb/X/CoFeB (X = Ge, NiAl, NiFeGe) topological heterostructures

https://mdr.nims.go.jp/datasets/a46752fd-8454-469f-b52b-9d39e75591e9

## File

- [clean manuscript to be submitted to JAP-2026-0331.docx](https://mdr.nims.go.jp/filesets/82b0a050-ff13-44d7-aec2-40fa84ba128f/download) ([Detail](https://mdr.nims.go.jp/filesets/82b0a050-ff13-44d7-aec2-40fa84ba128f.md))

## Id

a46752fd-8454-469f-b52b-9d39e75591e9

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2026-05-12T00:18:39.715349Z

## Updated at

2026-05-12T00:47:48.500074Z

## Published at

2026-05-12T03:27:01.154249Z

## Doi

https://doi.org/10.48505/nims.6281

## First published url

https://doi.org/10.1063/5.0313856

## Date published

2026-05-14

## Recorded date published

2026-5-14

## Resource type

journal_article

## Manuscript type

accepted_manuscript

## Collection



## Title

- title: Enhanced spin–orbit torque efficiency via interface engineering in BiSb/X/CoFeB
    (X = Ge, NiAl, NiFeGe) topological heterostructures
  title_type: original
  lang: en

## Description

- description: Interlayer engineering is crucial for achieving efficient spin–orbit
    torque (SOT) generation in topological insulator (TI)/ferromagnet–based heterostructures.
    In this work, we investigated the impact of semiconducting and intermetallic interlayers,
    i.e., Ge, NiAl, and NiFeGe, on SOT efficiency in topological BiSb/CoFeB heterostructures.
    Through comprehensive structural and transport analyses, we demonstrate that the
    Ge interlayer significantly enhances the performance. The insertion of a 1 nm-thick
    Ge layer significantly improves the crystallinity and orientation of BiSb, suppresses
    interfacial interdiffusion, and achieves a very low magnetic damping constant
    (αeff ~ 0.006). The optimized BiSb/Ge/CoFeB structure exhibits an enhanced SOT
    efficiency of ~50%, surpassing the performance of heterostructures without an
    interlayer, as well as those with NiAl or NiFeGe interlayers, which suffer from
    higher damping or reduced efficiency. Furthermore, we revealed that Ge thickness
    critically influences interfacial transparency, with excessive thickness degrading
    SOT efficiency. These findings establish Ge as an optimum interlayer material
    and indicate the importance of precise interface engineering to maximize charge-spin
    conversion in TI-based spintronic devices, paving the way for next-generation
    energy-efficient technologies.
  description_type: abstract
  lang: und

## Creator

- name: Rohiteswar Mondal
  role: author
- name: Zhenchao Wen
  role: author
  orcid: https://orcid.org/0000-0001-7496-1339
- name: Chandrasekhar Murapaka
  role: author
  orcid: https://orcid.org/0000-0002-0283-7037
- name: Seiji Mitani
  role: author
  orcid: https://orcid.org/0000-0002-1348-0774
- name: Hiroaki Sukegawa
  role: author
  orcid: https://orcid.org/0000-0002-4034-7848
- name: Quang Le
  role: author
  orcid: https://orcid.org/0000-0002-4991-5290
- name: Xiaoyong Liu
  role: author
  orcid: https://orcid.org/0000-0002-2661-8197
- name: Brian York
  role: author
- name: Maki Maeda
  role: author
  orcid: https://orcid.org/0009-0002-2808-0498

## Contact agent



## Publisher

organization: AIP Publishing

## Managing organization



## Keyword

- subject: interface engineering
  schema: not_defined
- subject: topological heterostructures
  schema: not_defined
- subject: BiSb/X/CoFeB (X = Ge, NiAl, NiFeGe)
  schema: not_defined

## Rights

- description: 'This article may be downloaded for personal use only. Any other use
    requires prior permission of the author and AIP Publishing. This article appeared
    in Rohiteswar Mondal, Zhenchao Wen, Chandrasekhar Murapaka, Seiji Mitani, Hiroaki
    Sukegawa, Quang Le, Xiaoyong Liu, Brian York, Maki Maeda; Enhanced spin–orbit
    torque efficiency via interface engineering in BiSb/X/CoFeB (X = Ge, NiAl, NiFeGe)
    topological heterostructures. J. Appl. Phys. 14 May 2026; 139 (18): 183903 and
    may be found at https://doi.org/10.1063/5.0313856.'
  identifier: http://rightsstatements.org/vocab/InC/1.0/

## Other identifier(s)



## Data origin

- data_origin_type: other

## Embargo



## Journal

- title: Journal of Applied Physics
  issn: '00218979'
  volume: '139'
  issue: '18'
  article_number: '183903'

## Conference



## Related item



## Funding

- funder_name: JICA Friendship Program 2.0
- funder_name: the International Cooperative Graduate Program in NIMS

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## Specimen



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## Fileset

- id: 82b0a050-ff13-44d7-aec2-40fa84ba128f
  filename: clean manuscript to be submitted to JAP-2026-0331.docx
  content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
  size: 1443661
  md5: 339683dd9ab1c4357a5901687da086bf

## Thumbnail

fileset_id: 82b0a050-ff13-44d7-aec2-40fa84ba128f
filename: clean manuscript to be submitted to JAP-2026-0331.docx