Terahertz single conductance quantum and topological phase transitions in topological insulator Bi2Se3 ultrathin films

Byung Cheol Park, Tae Hyeon Kim, Kyung Ik Sim, Boyoun Kang, Jeong Won Kim, Beongki Cho, Kwang Ho Jeong, Mann Ho Cho, Jae Hoon Kim

Research output: Contribution to journalArticlepeer-review

52 Citations (Scopus)


Strong spin-orbit interaction and time-reversal symmetry in topological insulators generate novel quantum states called topological surface states. Their study provides unique opportunities to explore exotic phenomena such as spin Hall effects and topological phase transitions, relevant to the development of quantum devices for spintronics and quantum computation. Although ultrahigh-vacuum surface probes can identify individual topological surface states, standard electrical and optical experiments have so far been hampered by the interference of bulk and quantum well states. Here, with terahertz time-domain spectroscopy of ultrathin Bi2Se3 films, we give evidence for topological phase transitions, a single conductance quantum per topological surface state, and a quantized terahertz absorbance of 2.9% (four times the fine structure constant). Our experiment demonstrates the feasibility to isolate, detect and manipulate topological surface states in the ambient at room temperature for future fundamental research on the novel physics of topological insulators and their practical applications.

Original languageEnglish
Article number6552
JournalNature communications
Publication statusPublished - 2015 Apr 23

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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