SPring-8, the large synchrotron radiation facility

A group of researchers from Hokkaido University, the University of Southampton, RIKEN, Kwansei Gakuin University, Kyoto University, and JASRI has successfully observed the ultrafast structural dynamics in a nanowire at the atomic level at the SPring-8 angstrom compact free electron laser (SACLA) facility.^*1 The group was led by Marcus C. Newton (assistant professor) of the Research Institute for Electronic Science, Hokkaido University (currently, a lecturer at the University of Southampton, UK), Yoshinori Nishino (professor) of the same institute, and Yoshihito Tanaka (Unit Leader) of the RIKEN SPring-8 Center (currently, a professor at the University of Hyogo and a visiting scientist at RIKEN).

Vanadium dioxide undergoes a phase transition, in which its electric properties and atomic arrangement are changed, upon external stimulation such as a change in temperature or exposure to light. Because of this, vanadium dioxide is expected to be used in switching devices (ON/OFF switches in electric circuits) and driving devices (actuators). However, the mechanism behind the phase transition of vanadium dioxide caused by light stimulation has remained unclear because it occurs in a very short time, and available experimental and theoretical methods are both limited.

The research group successfully observed transient ultrafast structural dynamics in a vanadium dioxide nanowire at the atomic level using XFEL. The key features of XFEL in this research were a very short pulse duration of approximately 10 fs (one femtosecond = one-quadrillionth of a second) and high coherency to enable the observation of atomic-level dynamics. Moreover, an advanced method combining the pump-probe method^*2 and coherent X-ray diffraction^*3 was adopted for the observation.

The obtained results demonstrated that XFEL has great potential for observing ultrafast structural dynamics at the atomic level. This will pave the way to developing innovative techniques for the ultrafast video recording of atoms and molecules in materials, and will contribute to clarifying various phase transition phenomena such as the high-temperature superconductivity of strongly correlated electron materials.^*4

The achievements of this research were published in the scientific journal Nano Letters on 14 May 2014.

Publication:
"Time-Resolved Coherent Diffraction of Ultrafast Structural Dynamics in a Single Nanowire"
Marcus C. Newton *†‡, Mayu Sao †, Yuta Fujisawa †, Rena Onitsuka , Tomoya Kawaguchi #, Kazuya Tokuda #, Takahiro Sato , Tadashi Togashi , Makina Yabashi , Tetsuya Ishikawa , Tetsu Ichitsubo #, Eiichiro Matsubara #, Yoshihito Tanaka , and Yoshinori Nishino †
† Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
‡ Department of Physics & Astronomy, University of Southampton, Southampton SO17 1BJ, U.K.
RIKEN SPring-8 Center, RIKEN, 1-1-1, Kouto, Sayo, Hyogo 679-5148, Japan
Department of Physics, School of Science and Technology, Kwansei Gakuin University, Gakuen, Sanda, Hyogo 669-1337, Japan
# Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan
Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
Nano Lett., 2014, 14 (5), pp 2413–2418
DOI: 10.1021/nl500072d
Publication Date (Web): April 17, 2014