Possible Persistence of Multiferroic Order down to Bilayer Limit of van der Waals Material NiI2

Hwiin Ju, Youjin Lee, Kwang Tak Kim, In Hyeok Choi, Chang Jae Roh, Suhan Son, Pyeongjae Park, Jae Ha Kim, Taek Sun Jung, Jae Hoon Kim, Kee Hoon Kim, Je Geun Park, Jong Seok Lee

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Realizing a state of matter in two dimensions has repeatedly proven a novel route of discovering new physical phenomena. Van der Waals (vdW) materials have been at the center of these now extensive research activities. They offer a natural way of producing a monolayer of matter simply by mechanical exfoliation. This work demonstrates that the possible multiferroic state with coexisting antiferromagnetic and ferroelectric orders persists down to the bilayer flake of NiI2. By exploiting the optical second-harmonic generation technique, both magnitude and direction of the ferroelectric order, arising from the cycloidal spin order, are successfully traced. The possible multiferroic state's transition temperature decreases from 58 K for the bulk to about 20 K for the bilayer. Our observation will spur extensive efforts to demonstrate multifunctionality in vdW materials, which have been tried mostly by using heterostructures of singly ferroic ones until now.

Original languageEnglish
Pages (from-to)5126-5132
Number of pages7
JournalNano letters
Issue number12
Publication statusPublished - 2021 Jun 23

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

All Science Journal Classification (ASJC) codes

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


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