Topological Phase Buried in a Chalcogenide Superlattice Monitored by Helicity-Dependent Kerr Measurement

Richarj Mondal, Yuki Aihara, Yuta Saito, Paul Fons, Alexander V. Kolobov, Junji Tominaga, Muneaki Hase

研究成果: Article査読

4 被引用数 (Scopus)


Chalcogenide superlattices (SLs), formed by the alternate stacking of GeTe and Sb2Te3 layers, also referred to as interfacial phase-change memory (iPCM), are a leading candidate for spin-based memory device applications. Theoretically, the iPCM structure has been predicted to form a three-dimensional topological insulator or Dirac semimetal phase depending on the constituent layer thicknesses. Here, we experimentally investigate the topological insulating nature of chalcogenide SLs using a helicity-dependent time-resolved Kerr measurement. The helicity-dependent Kerr signal is observed to exhibit a four-cycle oscillation with π/2 periodicity, suggesting the existence of a Dirac-like cone in some chalcogenide SLs. Furthermore, we found that increasing the thickness of the GeTe layer dramatically changed the periodicity, indicating a phase transition from a Dirac semimetal into a trivial insulator. Our results demonstrate that thickness-tuned chalcogenide SLs can play an important role in the manipulation of topological states, which may open up new possibilities for spintronic devices based on chalcogenide SLs.

ジャーナルACS Applied Materials and Interfaces
出版ステータスPublished - 2018 8月 8

ASJC Scopus subject areas

  • 材料科学(全般)


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