title: Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials.
abstract: 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.
authors: Nanoelectronics Research Institute, National Institute of Advanced Industrial Science &Technology (AIST), Tsukuba Central 5, Higashi 1-1-1,Tsukuba 305-8562, Japan.|RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Kirill V
authors: KV
authors: Mitrofanov
authors: Nanoelectronics Research Institute, National Institute of Advanced Industrial Science &Technology (AIST), Tsukuba Central 5, Higashi 1-1-1,Tsukuba 305-8562, Japan.|RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan.|Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5198, Japan.
authors: Paul
authors: P
authors: Fons
authors: Nanoelectronics Research Institute, National Institute of Advanced Industrial Science &Technology (AIST), Tsukuba Central 5, Higashi 1-1-1,Tsukuba 305-8562, Japan.
authors: Kotaro
authors: K
authors: Makino
authors: Division of Applied Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan.
authors: Ryo
authors: R
authors: Terashima
authors: Department of Science, Faculty of Education, Hirosaki University, 1 Bunkyo-cho, Hirosaki, Aomori 036-8560, Japan.
authors: Toru
authors: T
authors: Shimada
authors: Nanoelectronics Research Institute, National Institute of Advanced Industrial Science &Technology (AIST), Tsukuba Central 5, Higashi 1-1-1,Tsukuba 305-8562, Japan.|Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5198, Japan.
authors: Alexander V
authors: AV
authors: Kolobov
authors: Nanoelectronics Research Institute, National Institute of Advanced Industrial Science &Technology (AIST), Tsukuba Central 5, Higashi 1-1-1,Tsukuba 305-8562, Japan.
authors: Junji
authors: J
authors: Tominaga
authors: Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors: Valeria
authors: V
authors: Bragaglia
authors: Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors: Alessandro
authors: A
authors: Giussani
authors: Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors: Raffaella
authors: R
authors: Calarco
authors: Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors: Henning
authors: H
authors: Riechert
authors: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Takahiro
authors: T
authors: Sato
authors: Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5198, Japan.
authors: Tetsuo
authors: T
authors: Katayama
authors: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Kanade
authors: K
authors: Ogawa
authors: Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5198, Japan.
authors: Tadashi
authors: T
authors: Togashi
authors: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Makina
authors: M
authors: Yabashi
authors: ICFO - Institut de Ciències Fot òniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels, Barcelona, Spain.
authors: Simon
authors: S
authors: Wall
authors: X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Ave, Lemont, IL 60439, USA.
authors: Dale
authors: D
authors: Brewe
authors: Nanoelectronics Research Institute, National Institute of Advanced Industrial Science &Technology (AIST), Tsukuba Central 5, Higashi 1-1-1,Tsukuba 305-8562, Japan.|Division of Applied Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan.|RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Muneaki
authors: M
authors: Hase