Band gap opening at the Dirac point in Co/BiSbTeSe2(0001) system

TL;DR

This study demonstrates that sub-angstrom Co coverage on BiSbTeSe2(0001) opens a nonmagnetic band gap at the Dirac point, caused by chemical hybridization rather than magnetic effects, with the gap remaining stable across a range of temperatures.

Contribution

It reveals that Co adatoms induce a nonmagnetic band gap in topological surface states through chemical hybridization, not magnetic interactions.

Findings

Co coverage opens a band gap at the Dirac point.

The gap remains unchanged across 15-150 K temperature range.

Surface state protection is eliminated due to symmetry breaking.

Abstract

Sub-angstrom Co coverage, being deposited on BiSbTeSe2(0001) surface at 200-330 C, opens a band gap at the Dirac point, with the shift of the Dirac point position caused by RT adsorbate pre-deposition. Temperature dependent measurements in 15-150 K range have shown no band gap width change. This fact indicates the nonmagnetic nature of the gap which may be attributed to the chemical hybridization of surface states upon the introduction of Co adatoms, which decrease crystallographic symmetry and eliminate topological protection of the surface states.