Why phase-change media are fast and stable: A new approach to an old problem

Alexander V. Kolobov, Paul Fons, Junji Tominaga, Anatoly I. Frenkel, Alexei L. Ankuoinov, Spyros N. Yannopoulos, Konstantinos S. Andrikopoulos, Tomoya Uruga

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)


Present-day multimedia strongly relies on re-writable phase-change optical memories. We find that, different from current consensus Ge2Sb 2Te5 (GST), the material of choice in digital versatile discs-random access memory (DVD-RAM), possesses a structure similar to ferroelectric GeTe, namely that Ge and Sb atoms are located off-center giving rise to a net dipole moment. Amorphisation of both GeTe and GST results in a significant shortening of covalent bonds and a decrease in the mean-square relative displacement concomitant with a drastic change in the short-range order. We demonstrate that the order-disorder transition in GeTe and GST is primarily due to a flip of Ge atoms from an octahedral position into a tetrahedral position without rupture of strong covalent bonds. It is this nature of the transformation that ensures large changes in reflectivity, fast disk performance and repeatable switching over millions cycles.

Original languageEnglish
Pages (from-to)3345-3349
Number of pages5
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Issue number5 B
Publication statusPublished - 2005 May
Externally publishedYes


  • Armorphous-to-crystalline transition
  • Local structure
  • X-ray absorptionlihe structure (XAFS)

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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