Unconventional transformation of spin Dirac phase across a topological quantum phase transition

Su Yang Xu, Madhab Neupane, Ilya Belopolski, Chang Liu, Nasser Alidoust, Guang Bian, Shuang Jia, Gabriel Landolt, Batosz Slomski, J. Hugo Dil, Pavel P. Shibayev, Susmita Basak, Tay Rong Chang, Horng Tay Jeng, Robert J. Cava, Hsin Lin, Arun Bansil, M. Zahid Hasan

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The topology of a topological material can be encoded in its surface states. These surface states can only be removed by a bulk topological quantum phase transition into a trivial phase. Here we use photoemission spectroscopy to image the formation of protected surface states in a topological insulator as we chemically tune the system through a topological transition. Surprisingly, we discover an exotic spin-momentum locked, gapped surface state in the trivial phase that shares many important properties with the actual topological surface state in anticipation of the change of topology. Using a spin-resolved measurement, we show that apart from a surface bandgap these states develop spin textures similar to the topological surface states well before the transition. Our results offer a general paradigm for understanding how surface states in topological phases arise from a quantum phase transition and are suggestive for the future realization of Weyl arcs, condensed matter supersymmetry and other fascinating phenomena in the vicinity of a quantum criticality.

Original languageEnglish (US)
Article number6870
JournalNature communications
StatePublished - Apr 17 2015

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy


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