Gap-like feature observed in the non-magnetic topological insulators. (8th January 2020)

• Record Type: Journal Article
• Authors: Yilmaz, T; Pertsova, A; Hines, W; Vescovo, E; Kaznatcheev, K; Balatsky, A V; Sinkovic, B
• Is Part Of: Journal of physics. Volume 32:Number 14(2020)
• Publication Date: 2020-01-08
• Subjects: topological insulators -- time reversal symmetry -- ARPES; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ab6349
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: 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 Bi2 Se3 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.