AIP Advances (Dec 2014)

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

  • L. J. Collins-McIntyre,
  • M. D. Watson,
  • A. A. Baker,
  • S. L. Zhang,
  • A. I. Coldea,
  • S. E. Harrison,
  • A. Pushp,
  • A. J. Kellock,
  • S. S. P. Parkin,
  • G. van der Laan,
  • T. Hesjedal

DOI
https://doi.org/10.1063/1.4904900
Journal volume & issue
Vol. 4, no. 12
pp. 127136 – 127136-11

Abstract

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We report the growth of Mn-doped Bi2Se3 thin films by molecular beam epitaxy (MBE), investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), SQUID magnetometry and x-ray magnetic circular dichroism (XMCD). Epitaxial films were deposited on c-plane sapphire substrates by co-evaporation. The films exhibit a spiral growth mechanism typical of this material class, as revealed by AFM. The XRD measurements demonstrate a good crystalline structure which is retained upon doping up to ∼7.5 atomic-% Mn, determined by Rutherford backscattering spectrometry (RBS), and show no evidence of the formation of parasitic phases. However an increasing interstitial incorporation of Mn is observed with increasing doping concentration. A magnetic moment of 5.1 μB/Mn is obtained from bulk-sensitive SQUID measurements, and a much lower moment of 1.6 μB/Mn from surface-sensitive XMCD. At ∼2.5 K, XMCD at the Mn L2,3 edge, reveals short-range magnetic order in the films and indicates ferromagnetic order below 1.5 K.