skip to main content

Title: Quantum anomalous Hall effect and a nontrivial spin-texture in ultra-thin films of magnetic topological insulators

We study the evolution of quantum anomalous Hall (QAH) effect for a Z{sub 2} topological insulator (TI) thin films in a proximity induced magnetic phase by a realistic layered k·p model with interlayer coupling. We examine three different magnetic configurations in which ferromagnetic (FM) layer(s) is added either from one side (FM-TI), from both sides (FM-TI-FM), or homogeneously distributed (magnetically doped) in a TI slab. We map out the thickness-dependent topological phase diagram under various experimental conditions. The critical magnetic exchange energy for the emergence of QAH effect in the latter two cases decreases monotonically with increasing number of quintuple layers (QLs), while it becomes surprisingly independent of the film thickness in the former case. The gap size of the emergent QAH insulator depends on the non-magnetic “parent” gap of the TI thin film and is tuned by the FM exchange energy, opening a versatile possibility to achieve room-temperature QAH insulator in various topological nanomaterials. Finally, we find that the emergent spin-texture in the QAH effect is very unconventional, non-“hedgehog” type; and it exhibits a chiral out-of-plane spin-flip texture within the same valence band which is reminiscent of dynamical “skyrmion” pattern, except our results are in the momentum space.
Authors:
; ; ;  [1]
  1. Graphene Research Centre and Department of Physics, National University of Singapore, Singapore 117546 (Singapore)
Publication Date:
OSTI Identifier:
22410040
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHIRALITY; COUPLING; DOPED MATERIALS; ELECTRONIC STRUCTURE; FERROMAGNETIC MATERIALS; FERROMAGNETISM; HALL EFFECT; LAYERS; NANOMATERIALS; PHASE DIAGRAMS; SPIN; SPIN FLIP; TEMPERATURE RANGE 0273-0400 K; TEXTURE; THIN FILMS; TOPOLOGY; VALENCE