Spontaneous Decay of a Soft Optical Phonon in the Relaxor Ferroelectric PbMg1/3Nb2/3O3

Published

February 13, 2018

Author(s)

C. Stock, Peter M. Gehring, R. A. Ewings, Guangyong Xu, Jiefang Li, Dwight Viehland, Haosu Luo

Abstract

We report the spontaneous decay of a soft, optical phonon in a solid. Using neutron spectroscopy, we find that specific phonon lifetimes in the relaxor PbMg_1/3Nb_2/3O₃ are anomalously short within well-defined ranges of energy and momentum. This behavior is independent of ferroelectric order and occurs when the optical phonon with a specific energy and momentum can kinematically decay into two acoustic phonons with lower phase velocity.We interpret the well-known relaxor "waterfall" effect as a form of quasiparticle decay analogous to that previously reported in quantum spin liquids and quantum fluids.

Citation

Physical Review Materials

Volume

2

Issue

2

Pub Type

Journals

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Keywords

Lattice dynamics, phonons, quasiparticle decay, anharmonicity, relaxors, PMN, perovskite, neutron scattering

Citation

Stock, C. , Gehring, P. , Ewings, R. , Xu, G. , Li, J. , Viehland, D. and Luo, H. (2018), Spontaneous Decay of a Soft Optical Phonon in the Relaxor Ferroelectric PbMg_1/3Nb_2/3O₃, Physical Review Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925396 (Accessed October 14, 2025)