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

Journal Article · Tue Jan 14 00:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4861615· OSTI ID:22271256

Harrison, S. E.; Huo, Y.; Harris, J. S. ^[1]; Collins-McIntyre, L. J.; Li, S. ^[2]; Baker, A. A. ^[3]; Shelford, L. R.; Laan, G. van der ^[4]; Pushp, A.; Parkin, S. S. P. ^[5]; Arenholz, E. ^[6]

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1. Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)
2. Department of Physics, Stanford University, Stanford, California 94305 (United States)
3. Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom)
4. Magnetic Spectroscopy Group, Diamond Light Source, Didcot, Oxfordshire OX11 0DE (United Kingdom)
5. IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)
6. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

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 polarization effects can lead to the formation of magnetic order within the topological insulators.

• OSTI ID: 22271256
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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