Single crystal synthesis and surface electronic structure of Bi1.993Cr0.007Se3

Abstract

Topological insulators containing single atoms of magnetic metals are useful for studying the effects of magnetism on the topological properties of matter. Controlling the distribution of magnetic atoms remains a major issue during the synthesis of these materials, as the formation of clusters and/or unwanted precipitates competes energetically with the formation of dilute phases. Here, we report the synthesis of large Bi₂Se₃ single crystals with rhombohedral structure and extremely low concentration (0.15 at%) of substitutional Cr ions using the Bridgman method. After exfoliation, the crystals exhibit a topological surface state with an energy-momentum dispersion different from that of pristine Bi₂Se₃, due to the presence of an apparent energy gap at the Dirac point. The properties of this state are discussed in comparison with previous spectroscopic measurements of Cr-doped Bi₂Se₃ films.