Gap-like feature observed in the non-magnetic topological insulators

• Non-magnetic gap at the Dirac point of topological insulators remains an open question in the field. Here, we present angle-resolved photoemission spectroscopy experiments performed on Cr-doped Bi2Se3 and showed that the Dirac point is progressively buried by the bulk bands and a low spectral weight region in the vicinity of the Dirac point appears. These two mechanisms lead to spectral weight suppression region being mistakenly identified as an energy gap in earlier studies. We further calculated the band structure and found that the original Dirac point splits into two nodes due to the impurity resonant states and the energy separation between the nodes is the low density of state region which appears to be like an energy gap in potoemission experiments. We supported our arguments by presenting photoemission experiments carried out with on- and off- resonant photon energies. Our observation resolves the widely debated questions of apparent energy gap opening at the Dirac point without long range ferromagnetic order in topological insulators.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Keyword

ARPES

time reversal symmetry

topological insulators

Bismuth compounds

Chromium compounds

Energy gap

Photoelectron spectroscopy

Selenium compounds

Angle resolved photoemission spectroscopy

Energy separations

Long range ferromagnetic order

Photon energy

Resonant state

Spectral weight

Time reversal symmetries

Electric insulators

Publication and Content Type

ref (subject category)

art (subject category)