Magnetic Phase Transitions and transport properties of Heterostructures (MnBi₂Te₄)/(Bi₂Te₃)_n using First Principles

The interplay between magnetism and topology led to the realization of quantum anomalous Hall effect in heterostructures, exhibiting the axion insulator MnBi₂Te₄ and well-known topological insulators like the Bi₂Te₃ family [1]. The current study aims to explore the magneto-transport properties like anomalous Hall conductivity of heterostructures such as Bi₂Te₃/MnBi₂Te_4, which is an extension of previous study on Bi₂Se₃/Bi₂MnSe₄ reporting non-trivial topological surface states [2]. MnBi2Te4 is found to exhibit antiferromagnetic ordering, substantiated by ground state energy eigenvalues analysis. The Hubbard U value of 1.1 eV [3] is included to commensurate the electron correlation effect for Mn - ‘d’ orbitals. The amount of non-magnetic Bi₂Te₃ layers sandwiched between two antiferromagnetic MnBi₂Te₄ layers suppresses the interlayer exchange coupling between the two antiferromagnetic layers. Such is beneficial for quantized anomalous Hall conductivity at low intrinsic/extrinsic magnetic fields [4]. This inspires the examination of magnetic properties of the heterostructure forms, MnBi₂Te₄/(Bi₂Te₃)_n/MnBi₂Te₄ ,with n = 1 to n = 4 to minimize the interlayer exchange coupling between two MnBi2Te4 layers, leading to exotic magneto-transport properties like anomalous Hall conductivity.

[1] Haiming Deng et al., High-temperature quantum anomalous Hall regime in a MnBi₂Te₄/Bi₂Te₃ superlattice, Nature Physics, 17 (2021) 36–42

[2] Joseph A Hagmann et al., Molecular beam epitaxy growth and structure of self-assembled Bi₂Se₃/Bi₂MnSe₄ multilayer heterostructures, New J. Phys. 19 (2017) 085002

[3] Aki Pulkkinen et al., Coulomb correlation in noncollinear anti-ferromagnetic α-Mn, Phys. Rev. B. 101 (2020) 075115.

[4] M. Z. Shi et al., Magnetic and transport properties in the magnetic topological insulators MnBi₂Te₄(Bi₂Te₃)n (n = 1, 2), Phys. Rev. B. 100, (2019) 155144