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arXiv · 1309.5917

Dirac cone with helical spin polarization in ultrathin $α$-Sn(001) films

Yoshiyuki Ohtsubo·Patrick Le Fèvre·François Bertran·Amina Taleb-Ibrahimi
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Abstract

Spin-split two-dimensional electronic states have been observed on ultrathin Sn(001) films grown on InSb(001) substrates. Angle-resolved photoelectron spectroscopy (ARPES) performed on these films revealed Dirac-cone-like linear dispersion around the $\barΓ$ point of surface Brillouin zone, suggesting nearly massless electrons belonging to 2D surface states. The states disperse across a bandgap between bulk-like quantum well states in the films. Moreover, both circular dichroism of ARPES and spin-resolved ARPES studies show helical spin polarization of the Dirac-cone-like surface states, suggesting a topologically protected character as in a bulk topological insulator (TI). These results indicate that a quasi-3D TI phase can be realized in ultrathin films of zero-gap semiconductors.

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Yoshiyuki Ohtsubo, Patrick Le Fèvre, François Bertran, Amina Taleb-Ibrahimi. 2013-11-21. Dirac cone with helical spin polarization in ultrathin $α$-Sn(001) films. https://doi.org/10.1103/physrevlett.111.216401

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