Research Abstract


Tunable Dirac cone in the topological insulator Bi2-xSbxTe3-ySey

2012年1月24日 Nature Communications 3 : 636 doi: 10.1038/ncomms1639 (2012)


荒金 俊行1, 佐藤 宇史2, 相馬 清吾1, 高坂 研一郎2, 中山 耕輔2, 小松 誠2, 高橋 隆1,2, Zhi Ren3, 瀬川 耕司3 & 安藤 陽一3

  1. 東北大学原子分子材料科学高等研究機構
  2. 東北大学大学院理学研究科物理学専攻
  3. 大阪大学 産業科学研究所

The three-dimensional topological insulator is a quantum state of matter characterized by an insulating bulk state and gapless Dirac cone surface states. Device applications of topological insulators require a highly insulating bulk and tunable Dirac carriers, which has so far been difficult to achieve. Here we demonstrate that Bi2-xSbxTe3-ySey is a system that simultaneously satisfies both of these requirements. For a series of compositions presenting bulk-insulating transport behaviour, angle-resolved photoemission spectroscopy reveals that the chemical potential is always located in the bulk band gap, whereas the Dirac cone dispersion changes systematically so that the Dirac point moves up in energy with increasing x, leading to a sign change of the Dirac carriers at x~0.9. Such a tunable Dirac cone opens a promising pathway to the development of novel devices based on topological insulators.