Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials

Kirill V. Mitrofanov, Paul Fons, Kotaro Makino, Ryo Terashima, Toru Shimada, Alexander V. Kolobov, Junji Tominaga, Valeria Bragaglia, Alessandro Giussani, Raffaella Calarco, Henning Riechert, Takahiro Sato, Tetsuo Katayama, Kanade Ogawa, Tadashi Togashi, Makina Yabashi, Simon Wall, Dale Brewe, Muneaki Hase

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30 Citations (Scopus)


Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change on picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort X-ray probe is used to show the temporal separation of electronic and thermal effects in a long-lived (>100 ps) transient metastable state of Ge2Sb2Te5 with muted interatomic interaction induced by a weakening of resonant bonding. Due to a specific electronic state, the lattice undergoes a reversible nondestructive modification over a nanoscale region, remaining cold for 4 ps. An independent time-resolved X-ray absorption fine structure experiment confirms the existence of an intermediate state with disordered bonds. This newly unveiled effect allows the utilization of non-thermal ultra-fast pathways enabling artificial manipulation of the switching process, ultimately leading to a redefined speed limit, and improved energy efficiency and reliability of phase-change memory technologies.

Original languageEnglish
Article number20633
JournalScientific reports
Publication statusPublished - 2016 Feb 12
Externally publishedYes

ASJC Scopus subject areas

  • General


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