2021/01/24 by Anh Pham, Ling‐Jie Zhou, Pham, Anh +9
Engineering · Physics and Astronomy · #FOS: Physical sciences #Magnetic Field Sensors Techniques #Materials Science (cond-mat.mtrl-sci) #Quantum and electron transport phenomena #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2101.09829
openalex publication_date 2021/01/24 · openalex created_date 2021/02/01 · openalex updated_date 2026/07/28
Heterostructures between topological insulators (TI) and magnetic insulators represent a pathway to realize the quantum anomalous Hall effect (QAHE). Using density functional theory based systematic screening and investigation of thermodynamic, magnetic and topological properties of heterostructures, we demonstrate that forming a type-I heterostructure between a wide gap antiferromagnetic insulator Cr2O3 and a TI-film, such as Sb2Te3, can lead to pinning of the Fermi-level at the center of the gap, even when magnetically doped. Cr-doping in the heterostructure increases the gap to ∼ 64.5 meV, with a large Zeeman energy from the interfacial Cr dopants, thus overcoming potential metallicity due to band bending effects. By fitting the band-structure around the Fermi-level to a 4-band k.p model Hamiltonian, we show that Cr doped Sb2Te3/Cr2O3 is a Chern insulator with a Chern number C = -1. Transport calculations further show chiral edge-modes localized at the top/bottom of the TI-film to be the dominant current carriers in the material. Our predictions of a large interfacial magnetism due to Cr-dopants, that coupled antiferromagnetically to the AFM substrate is confirmed by our polarised neutron reflectometry measurements on MBE grown Cr doped Sb2Te3/Cr2O3 heterostructures, and is consistent with a positive exchange bias measured in such systems recently. Consequently, Cr doped Sb2Te3/Cr2O3 heterostructure represents a promising platform for the development of functional topological magnetic devices, with high tunability.