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

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)26781-26786
Number of pages6
JournalACS Applied Materials and Interfaces
Volume10
Issue number31
DOIs
Publication statusPublished - 2018 Aug 8
Externally publishedYes

Keywords

  • chalcogenide superlattice
  • Dirac semimetal
  • optical Kerr effect
  • phase-change material
  • time-resolved Kerr spectroscopy
  • topological insulator

ASJC Scopus subject areas

  • Materials Science(all)

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