Surface Electronic Structure of Cr Doped Bi[sub.2]Se[sub.3] Single Crystals

Here, by using angle-resolved photoemission spectroscopy, we showed that Bi[sub.2−x] Cr[sub.x] Se[sub.3] single crystals have a distinctly well-defined band structure with a large bulk band gap and undistorted topological surface states. These spectral features are unlike their thin film forms in which a large nonmagnetic gap with a distorted band structure was reported. We further provide laser-based high resolution photoemission data which reveal a Dirac point gap even in the pristine sample. The gap becomes more pronounced with Cr doping into the bulk of Bi[sub.2] Se[sub.3] . These observations show that the Dirac point can be modified by the magnetic impurities as well as the light source.