title: Signature of a polyamorphic transition in the THz spectrum of vitreous GeO2.
abstract: The THz spectrum of density fluctuations, S(Q, ω), of vitreous GeO2 at ambient temperature was measured by inelastic x-ray scattering from ambient pressure up to pressures well beyond that of the known α-quartz to rutile polyamorphic (PA) transition. We observe significant differences in the spectral shape measured below and above the PA transition, in particular, in the 30-80 meV range. Guided by first-principle lattice dynamics calculations, we interpret the changes in the phonon dispersion as the evolution from a quartz-like to a rutile-like coordination. Notably, such a crossover is accompanied by a cusp-like behavior in the pressure dependence of the elastic response of the system. Overall, the presented results highlight the complex fingerprint of PA phenomena on the high-frequency phonon dispersion.
authors.affiliation: National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cunsolo
authors.affiliation: American Physical Society, 1 Research Road, Ridge, New York 11961, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: Chaminda N
authors.initials: CN
authors.lastname: Kodituwakku
authors.affiliation: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA.
authors.forename: Shibing
authors.initials: S
authors.lastname: Wang
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités - UPMC, Muséum National d'Historie Naturelle, IRD Unité 206, 75252 Paris, France.
authors.forename: Daniele
authors.initials: D
authors.lastname: Antonangeli
authors.affiliation: Sincrotrone Trieste, S.S. 14 km 163,5 in AREA Science Park 34012 Basovizza, Trieste, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Bencivenga
authors.affiliation: Sincrotrone Trieste, S.S. 14 km 163,5 in AREA Science Park 34012 Basovizza, Trieste, Italy.|Dipartimento di Fisica, Università degli Studi di Trieste, I-34127 Trieste, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Battistoni
authors.affiliation: European Synchrotron Radiation Facility (ESRF), 71 avenue des Martyrs, 38043 Grenoble, France.
authors.forename: Roberto
authors.initials: R
authors.lastname: Verbeni
authors.affiliation: Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo 679-5198, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsutsui
authors.affiliation: Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo 679-5198, Japan.|SPring-8/RIKEN, Hyogo 679-5148, Japan.
authors.forename: Alfred Q R
authors.initials: AQ
authors.lastname: Baron
authors.affiliation: Geophysical Laboratory Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, USA.|Center for High Pressure Science &Technology Advanced Research, Pudong, Shanghai, 201203, China.
authors.forename: Ho-Kwang
authors.initials: HK
authors.lastname: Mao
authors.affiliation: National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: Dima
authors.initials: D
authors.lastname: Bolmatov
authors.affiliation: National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.
authors.forename: Yong Q
authors.initials: YQ
authors.lastname: Cai