Quantum Anomalous Hall Effect in Magnetic Doped Topological Insulators and Ferromagnetic Spin‐Gapless Semiconductors—A Perspective Review. Issue 42 (11th September 2020)

• Record Type: Journal Article
• Authors: Nadeem, Muhammad; Hamilton, Alex R.; Fuhrer, Michael S.; Wang, Xiaolin
• Is Part Of: Small. Volume 16:Issue 42(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-09-11
• Subjects: ferromagnetic semiconductors -- magnetic topological insulators -- quantum anomalous hall effect -- spin‐gapless semiconductors; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201904322
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Quantum anomalous Hall effect, with a trademark of dissipationless chiral edge states for electronics/spintronics transport applications, can be realized in materials with large spin–orbit coupling and strong intrinsic magnetization. After Haldane's seminal proposal, several models have been presented to control/enhance the spin–orbit coupling and intrinsic magnetic exchange interaction. After brief introduction of Haldane model for spineless fermions, following three fundamental quantum anomalous Hall models are discussed in this perspective review: i) low‐energy effective four band model for magnetic‐doped topological insulator (Bi, Sb)2 Te3 thin films, ii) four band tight‐binding model for graphene with magnetic adatoms, and iii) two (three) band spinful tight‐binding model for ferromagnetic spin‐gapless semiconductors with honeycomb (kagome) lattice where ground state is intrinsically ferromagnetic. These models cover 2D Dirac materials hosting spinless, spinful, and spin‐degenerate Dirac points where various mass terms open bandgap and lead to quantum anomalous Hall effect. With emphasis on the topological phase transition driven by ferromagnetic exchange interaction and its interplay with spin–orbit‐coupling, various symmetry constraints on the nature of mass term and the materialization of these models are discussed. This study will shed light on the fundamental theoretical perspectives of quantum anomalous Hall materials. Abstract : Prototypical models for quantum anomalous Hall effect in graphene, magnetically doped topological insulators, and ferromagnetic spin‐gapless semiconductors are studied. While bulk band topology of magnetically doped topological insulators is associated with inverted band structure, nontrivial Chern number in graphene and ferromagnetic spin‐gapless semiconductors is indebted to the next‐nearest‐neighbor tunneling and the associated phase acquired by electrons while hopping in the local magnetic field.