TY - JOUR
T1 - Longitudinal acoustic and higher-energy excitations in the liquid phase-change material Ge2Sb2Te5
AU - Inui, M.
AU - Kajihara, Y.
AU - Hosokawa, S.
AU - Chiba, A.
AU - Nakajima, Y.
AU - Matsuda, K.
AU - Tsuchiya, Y.
AU - Stellhorn, J. R.
AU - Hagiya, T.
AU - Uchiyama, H.
AU - Tsutsui, S.
AU - Baron, A. Q.R.
N1 - Funding Information:
We would like to thank Dr. Shinji Kohara, Professor Robert O. Jones, and Professor Jaakko Akola for their valuable discussion. The authors acknowledge Ministry of Education, Culture, Sports, Science and Technology in Japan and the Japan Society for the Promotion of Science (JSPS) for a Grant-in-Aid for Scientific Research (A) (Grant No. 20244061) and Scientific Research (B) (Grant No. 16340114). The synchrotron radiation experiments were performed at the SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposals No. 2019A1195, No. 2018B1221, and No. 2013B1269).
Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/8/1
Y1 - 2021/8/1
N2 - The dynamic structure factor S(Q,E) of liquid Ge2Sb2Te5 has been obtained by inelastic x-ray scattering, where Q and E are momentum and energy transfer, respectively. The dispersion curve of the longitudinal acoustic excitation energy exhibits flat-topped Q dependence similarly to that in liquid GeTe and liquid Bi, where the local structure is modulated by Peierls distortion. The flat-topped energy in liquid Ge2Sb2Te5 is split into low and high energy parts arising from Sb-Te and Ge-Te correlations, respectively. Furthermore, the high energy part depends on Q like an optical mode with decreasing Q to zero, and it approaches the vibrational energy of fourfold coordinated Ge atoms with octahedral configurations. The result indicates that a majority of Ge in the liquid stays in octahedral order as predicted by first-principles molecular dynamics simulations.
AB - The dynamic structure factor S(Q,E) of liquid Ge2Sb2Te5 has been obtained by inelastic x-ray scattering, where Q and E are momentum and energy transfer, respectively. The dispersion curve of the longitudinal acoustic excitation energy exhibits flat-topped Q dependence similarly to that in liquid GeTe and liquid Bi, where the local structure is modulated by Peierls distortion. The flat-topped energy in liquid Ge2Sb2Te5 is split into low and high energy parts arising from Sb-Te and Ge-Te correlations, respectively. Furthermore, the high energy part depends on Q like an optical mode with decreasing Q to zero, and it approaches the vibrational energy of fourfold coordinated Ge atoms with octahedral configurations. The result indicates that a majority of Ge in the liquid stays in octahedral order as predicted by first-principles molecular dynamics simulations.
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U2 - 10.1103/PhysRevB.104.064202
DO - 10.1103/PhysRevB.104.064202
M3 - Article
AN - SCOPUS:85113171548
VL - 104
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 2469-9950
IS - 6
M1 - 064202
ER -