Ultrafast Carrier-Lattice Interactions and Interlayer Modulations of Bi2Se3by X-ray Free-Electron Laser Diffraction

Sungwon Kim, Youngsam Kim, Jaeseung Kim, Sungwook Choi, Kyuseok Yun, Dongjin Kim, Soo Yeon Lim, Sunam Kim, Sae Hwan Chun, Jaeku Park, Intae Eom, Kyung Sook Kim, Tae Yeong Koo, Yunbo Ou, Ferhat Katmis, Haidan Wen, Anthony Dichiara, Donald A. Walko, Eric C. Landahl, Hyeonsik CheongEunji Sim, Jagadeesh Moodera, Hyunjung Kim

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


As a 3D topological insulator, bismuth selenide (Bi2Se3) has potential applications for electrically and optically controllable magnetic and optoelectronic devices. Understanding the coupling with its topological phase requires studying the interactions of carriers with the lattice on time scales down to the subpicosecond regime. Here, we investigate the ultrafast carrier-induced lattice contractions and interlayer modulations in Bi2Se3 thin films by time-resolved diffraction using an X-ray free-electron laser. The lattice contraction depends on the carrier concentration and is followed by an interlayer expansion accompanied by oscillations. Using density functional theory and the Lifshitz model, the initial contraction can be explained by van der Waals force modulation of the confined free carrier layers. Our theoretical calculations suggest that the band inversion, related to a topological phase transition, is modulated by the expansion of the interlayer distance. These results provide insights into the topological phase control by light-induced structural change on ultrafast time scales.

Original languageEnglish
Pages (from-to)8554-8562
Number of pages9
JournalNano letters
Issue number20
Publication statusPublished - 2021 Oct 27

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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