Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator

• Published in: Science (American Association for the Advancement of Science) Vol. 329; no. 5992; pp. 659 - 662
• Main Authors: Chen, Y.L, Chu, J.-H, Analytis, J.G, Liu, Z.K, Igarashi, K, Kuo, H.-H, Qi, X.L, Mo, S.K, Moore, R.G, Lu, D.H, Hashimoto, M, Sasagawa, T, Zhang, S.C, Fisher, I.R, Hussain, Z, Shen, Z.X
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 06-08-2010; The American Association for the Advancement of Science
• Subjects: Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dopants; Doping; Electron density of states and band structure of crystalline solids; Electron states; Electronic publishing; Electronic structure; Energy gap; Exact sciences and technology; Fermi surfaces; Fermions; Gaps; Insulators; Materials; Materials science; Mathematical surfaces; Other inorganic compounds; Photons; Physics; Quantum physics; Semiconductor doping; Symmetry; Topology; Transport phenomena; Bismuth selenides; Band structure; Topological insulator; Energy gap; Fermi level; Doping; Dirac equation; Angle resolved photoemission spectroscopy; Symmetry breaking; Time reversal
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1189924

In addition to a bulk energy gap, topological insulators accommodate a conducting, linearly dispersed Dirac surface state. This state is predicted to become massive if time reversal symmetry is broken, and to become insulating if the Fermi energy is positioned inside both the surface and bulk gaps. We introduced magnetic dopants into the three-dimensional topological insulator dibismuth triselenide (Bi₂Se₃) to break the time reversal symmetry and further position the Fermi energy inside the gaps by simultaneous magnetic and charge doping. The resulting insulating massive Dirac fermion state, which we observed by angle-resolved photoemission, paves the way for studying a range of topological phenomena relevant to both condensed matter and particle physics.