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Study of Gd-doped Bi2Te3 thin films: Molecular beam epitaxy growth and magnetic properties

DOI: 10.1063/1.4861615 DOI Help

Authors: S. E. Harrison (Stanford University,) , L. Collins-mcintyre (University of Oxford) , S. Li (Stanford University,) , A. Baker (Diamond Light Source) , L. Shelford (Diamond Light Source) , Y. Huo (Stanford University) , A. Pushp (IBM Almaden Research Center,) , S. S. P. Parkin (IBM Almaden Research Center,) , J. S. Harris (Stanford University) , E. Arenholz (Lawrence Berkeley National Laboratory) , G. Van Der Laan (Diamond Light Source) , T. Hesjedal (University of Oxford)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Journal Of Applied Physics , VOL 115 (2)

State: Published (Approved)
Published: January 2014

Abstract: 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. GdBiTe3 with a Gd:Bi ratio of 1:1 is a proposed QAHE system, however, the reported solubility limit for Gd doping into Bi2Te3 bulk crystals is between ?0.01 and 0.05. We present a magnetic study of molecular beam epitaxy grown (Gd x Bi1– x )2Te3 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 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 Gd3+ ions, which are substitutional on Bi sites in the Bi2Te3 lattice, exhibit a large atomic moment of ?7?? B , as determined by bulk-sensitive superconducting quantum interference device magnetometry. Surface oxidation and the formation of Gd2O3 lead to a reduced moment of ?4?? 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.

Journal Keywords: 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

Subject Areas: Physics, Materials


Instruments: I06-Nanoscience , I10-Beamline for Advanced Dichroism

Other Facilities: Advanced Light Source