Co atoms on Bi${}_2$Se${}_3$ revealing a coverage dependent spin reorientation transition

Abstract

We investigate Co nanostructures on Bi${}_2$Se${}_3$ by means of scanning tunneling microscopy and spectroscopy [STM/STS], X-ray absorption spectroscopy [XAS], X-ray magnetic dichroism [XMCD] and calculations using the density functional theory [DFT]. In the single adatom regime we find two different adsorption sites by STM. Our calculations reveal these to be the fcc and hcp hollow sites of the substrate. STS shows a pronounced peak for only one species of the Co adatoms indicating different electronic properties of both types. These are explained on the basis of our DFT calculations by different hybridizations with the substrate. Using XMCD we find a coverage dependent spin reorientation transition from easy-plane toward out-of-plane. We suggest clustering to be the predominant cause for this observation.

10 pages, 4 figures

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• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
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Cited by in corpus (6)

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• Electronic properties of Bi${}_2$Se${}_3$ dopped by $3d$ transition metal (Mn, Fe, Co, or Ni) ions
• Structural and electronic properties of the pure and stable elemental 3D topological Dirac semimetal $\alpha$-Sn
• Low coverage surface diffusion in complex energy landscapes: Analytical solution and application to intercalation in topological insulators
• Induced Spin-texture at 3$d$ Transition Metal/Topological Insulator Interfaces
• Highly tunable magnetic coupling in ultrathin topological insulator films due to impurity resonances