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Title: Study of Gd-doped Bi{sub 2}Te{sub 3} thin films: Molecular beam epitaxy growth and magnetic properties

Incorporation of magnetic dopants into topological insulators to break time-reversal symmetry is a prerequisite for observing the quantum anomalous Hall (QAHE) effect and other novel magnetoelectric phenomena. GdBiTe{sub 3} with a Gd:Bi ratio of 1:1 is a proposed QAHE system, however, the reported solubility limit for Gd doping into Bi{sub 2}Te{sub 3} bulk crystals is between ∼0.01 and 0.05. We present a magnetic study of molecular beam epitaxy grown (Gd{sub x}Bi{sub 1–x}){sub 2}Te{sub 3} thin films with a high Gd concentration, up to x ≈ 0.3. Magnetometry reveals that the films are paramagnetic down to 1.5 K. X-ray magnetic circular dichroism at the Gd M{sub 4,5} edge at 1.5 K reveals a saturation field of ∼6 T, and a slow decay of the magnetic moment with temperature up to 200 K. The Gd{sup 3+} ions, which are substitutional on Bi sites in the Bi{sub 2}Te{sub 3} lattice, exhibit a large atomic moment of ∼7 μ{sub B}, as determined by bulk-sensitive superconducting quantum interference device magnetometry. Surface oxidation and the formation of Gd{sub 2}O{sub 3} lead to a reduced moment of ∼4 μ{sub B} as determined by surface-sensitive x-ray magnetic circular dichroism. Their large atomic moment makes these films suitable for incorporation into heterostructures, where interface polarizationmore » effects can lead to the formation of magnetic order within the topological insulators.« less
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [2] ;  [4] ; ;  [5] ; ;  [6] ;  [7]
  1. Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)
  2. Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom)
  3. Department of Physics, Stanford University, Stanford, California 94305 (United States)
  4. (United Kingdom)
  5. Magnetic Spectroscopy Group, Diamond Light Source, Didcot, Oxfordshire OX11 0DE (United Kingdom)
  6. IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)
  7. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
Publication Date:
OSTI Identifier:
22271256
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 2; Other Information: (c) 2014 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; BISMUTH TELLURIDES; CRYSTALS; DOPED MATERIALS; ELECTRICAL PROPERTIES; GADOLINIUM IONS; GADOLINIUM OXIDES; INTERFACES; MAGNETIC CIRCULAR DICHROISM; MAGNETIC MOMENTS; MAGNETIC PROPERTIES; MOLECULAR BEAM EPITAXY; OXIDATION; PARAMAGNETISM; POLARIZATION; SQUID DEVICES; SURFACES; THIN FILMS; X RADIATION