Spin transport properties in a topological insulator sandwiched between two-dimensional magnetic layers

Nezhat Pournaghavi; Banasree Sadhukhan; Anna Delin

doi:10.1038/s41598-024-80694-7

Spin transport properties in a topological insulator sandwiched between two-dimensional magnetic layers

Sci Rep. 2025 Jan 17;15(1):2255. doi: 10.1038/s41598-024-80694-7.

Authors

Nezhat Pournaghavi^{1

2

3}, Banasree Sadhukhan^{4

5

6}, Anna Delin^{7

8

9}

Affiliations

¹ Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691, Stockholm, Sweden. [email protected].
² Department of Physics and Astronomy, Uppsala University, 516, SE-75120, Uppsala, Sweden. [email protected].
³ Department of Physics, University of Texas at Austin, Austin, TX, 78712, USA. [email protected].
⁴ Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691, Stockholm, Sweden.
⁵ Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai, Tamil Nadu, 603203, India.
⁶ Tata Institute of Fundamental Research, Hyderabad, Telangana, 500046, India.
⁷ Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691, Stockholm, Sweden. [email protected].
⁸ Swedish e-Science Research Center (SeRC), KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden. [email protected].
⁹ Wallenberg Initiative Materials Science for Sustainability (WISE), KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden. [email protected].

PMID: 39824892
DOI: 10.1038/s41598-024-80694-7

Abstract

Non-trivial band topology along with magnetism leads to different novel quantum phases. When time-reversal symmetry is broken in three-dimensional topological insulators (TIs) through, e.g., the proximity effect, different phases such as the quantum Hall phase or the quantum anomalous Hall(QAH) phase emerge, displaying interesting transport properties for spintronic applications. The QAH phase displays sidewall chiral edge states, which leads to the QAH effect. We have considered a heterostructure consisting of a TI, namely Bi[Formula: see text]Se[Formula: see text], sandwiched between two two-dimensional ferromagnetic monolayers of CrI[Formula: see text], to study how its topological and transport properties change due to the proximity effect. Combining DFT and tight-binding calculations, along with non-equilibrium Green's function formalism, we show that a well-defined exchange gap appears in the band structure in which spin-polarised edge states flow. In a finite slab, the nature of the surface states depends on both the cross-section and thickness of the system. Therefore, we also study the width and finite-size effects on the transmission and topological properties of this magnetised TI nanoribbon.