Black phosphorus as a bipolar pseudospin semiconductor

Sung Won Jung, Sae Hee Ryu, Woo Jong Shin, Yeongsup Sohn, Minjae Huh, Roland J. Koch, Chris Jozwiak, Eli Rotenberg, Aaron Bostwick, Keun Su Kim

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)


Semiconductor devices rely on the charge and spin of electrons, but there is another electronic degree of freedom called pseudospin in a two-level quantum system1 such as a crystal consisting of two sublattices2. A potential way to exploit the pseudospin of electrons in pseudospintronics3–5 is to find quantum matter with tunable and sizeable pseudospin polarization. Here, we propose a bipolar pseudospin semiconductor, where the electron and hole states have opposite net pseudospin polarization. We experimentally identify such states in anisotropic honeycomb crystal—black phosphorus. By sublattice interference of photoelectrons, we find bipolar pseudospin polarization greater than 95% that is stable at room temperature. This pseudospin polarization is identified as a consequence of Dirac cones merged in the highly anisotropic honeycomb system6,7. The bipolar pseudospin semiconductor, which is a pseudospin analogue of magnetic semiconductors, is not only interesting in itself, but also might be useful for pseudospintronics.

Original languageEnglish
Pages (from-to)277-281
Number of pages5
JournalNature materials
Issue number3
Publication statusPublished - 2020 Mar 1

Bibliographical note

Publisher Copyright:
© 2020, The Author(s), under exclusive licence to Springer Nature Limited.

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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