Symmetry-breaking dynamical pattern and localization observed in the equilibrium vibrational spectrum of NaI

M. E. Manley; D. L. Abernathy; N. I. Agladze; A. J. Sievers

doi:10.1038/srep00004

Symmetry-breaking dynamical pattern and localization observed in the equilibrium vibrational spectrum of NaI

M. E. Manley, D. L. Abernathy, N. I. Agladze, A. J. Sievers

Direct Geometry

Research output: Contribution to journal › Article › peer-review

34 Scopus citations

Abstract

Intrinsic localized modes (ILMs)-also known as discrete breathers-are localized excitations that form without structural defects in discrete nonlinear lattices. For crystals in thermal equilibrium ILMs were proposed to form randomly, an idea used to interpret temperature activated signatures of ILMs in α ±-U and NaI. Here, however, we report neutron scattering measurements of lattice vibrations in NaI that provide evidence of an underlying organization: (i) with small temperature changes ILMs move as a unit back-and-forth between [111] and [011] orientations, and (ii) when [011] ILMs lock in at 636 K the transverse optic (TO) mode splits into three modes with symmetry-breaking dynamical structure resembling that of a superlattice, but there are no superlattice Bragg reflections and the pattern itself has crystal momentum. We conclude that this dynamical pattern is not derived from the rearrangement of atoms but from a coherent arrangement of ILMs decorating the crystal lattice in equilibrium.

Original language	English
Article number	4
Journal	Scientific Reports
Volume	1
DOIs	https://doi.org/10.1038/srep00004
State	Published - 2011

Funding

Work was partly performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344. Research at Oak Ridge National Laboratory’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The Cornell effort was supported by NSF grant DMR-0906491. M.E.M acknowledges helpful correspondence with P. S. Riseborough. A. J. S. thanks J. B. Page, J. P. Sethna, and V. M. Burlakov for insightful comments.

Funders	Funder number
Scientific User Facilities Division
National Science Foundation	DMR-0906491
U.S. Department of Energy
Directorate for Mathematical and Physical Sciences	0906491
Basic Energy Sciences
Lawrence Livermore National Laboratory	DE-AC52-07NA27344
Oak Ridge National Laboratory

Access to Document

10.1038/srep00004

Cite this

@article{b4d538b53cf64a09a1536eddc3a2845e,

title = "Symmetry-breaking dynamical pattern and localization observed in the equilibrium vibrational spectrum of NaI",

abstract = "Intrinsic localized modes (ILMs)-also known as discrete breathers-are localized excitations that form without structural defects in discrete nonlinear lattices. For crystals in thermal equilibrium ILMs were proposed to form randomly, an idea used to interpret temperature activated signatures of ILMs in α ±-U and NaI. Here, however, we report neutron scattering measurements of lattice vibrations in NaI that provide evidence of an underlying organization: (i) with small temperature changes ILMs move as a unit back-and-forth between [111] and [011] orientations, and (ii) when [011] ILMs lock in at 636 K the transverse optic (TO) mode splits into three modes with symmetry-breaking dynamical structure resembling that of a superlattice, but there are no superlattice Bragg reflections and the pattern itself has crystal momentum. We conclude that this dynamical pattern is not derived from the rearrangement of atoms but from a coherent arrangement of ILMs decorating the crystal lattice in equilibrium.",

author = "Manley, {M. E.} and Abernathy, {D. L.} and Agladze, {N. I.} and Sievers, {A. J.}",

year = "2011",

doi = "10.1038/srep00004",

language = "English",

volume = "1",

journal = "Scientific Reports",

issn = "2045-2322",

publisher = "Nature Research",

}

TY - JOUR

T1 - Symmetry-breaking dynamical pattern and localization observed in the equilibrium vibrational spectrum of NaI

AU - Manley, M. E.

AU - Abernathy, D. L.

AU - Agladze, N. I.

AU - Sievers, A. J.

PY - 2011

Y1 - 2011

N2 - Intrinsic localized modes (ILMs)-also known as discrete breathers-are localized excitations that form without structural defects in discrete nonlinear lattices. For crystals in thermal equilibrium ILMs were proposed to form randomly, an idea used to interpret temperature activated signatures of ILMs in α ±-U and NaI. Here, however, we report neutron scattering measurements of lattice vibrations in NaI that provide evidence of an underlying organization: (i) with small temperature changes ILMs move as a unit back-and-forth between [111] and [011] orientations, and (ii) when [011] ILMs lock in at 636 K the transverse optic (TO) mode splits into three modes with symmetry-breaking dynamical structure resembling that of a superlattice, but there are no superlattice Bragg reflections and the pattern itself has crystal momentum. We conclude that this dynamical pattern is not derived from the rearrangement of atoms but from a coherent arrangement of ILMs decorating the crystal lattice in equilibrium.

AB - Intrinsic localized modes (ILMs)-also known as discrete breathers-are localized excitations that form without structural defects in discrete nonlinear lattices. For crystals in thermal equilibrium ILMs were proposed to form randomly, an idea used to interpret temperature activated signatures of ILMs in α ±-U and NaI. Here, however, we report neutron scattering measurements of lattice vibrations in NaI that provide evidence of an underlying organization: (i) with small temperature changes ILMs move as a unit back-and-forth between [111] and [011] orientations, and (ii) when [011] ILMs lock in at 636 K the transverse optic (TO) mode splits into three modes with symmetry-breaking dynamical structure resembling that of a superlattice, but there are no superlattice Bragg reflections and the pattern itself has crystal momentum. We conclude that this dynamical pattern is not derived from the rearrangement of atoms but from a coherent arrangement of ILMs decorating the crystal lattice in equilibrium.

UR - http://www.scopus.com/inward/record.url?scp=80155170088&partnerID=8YFLogxK

U2 - 10.1038/srep00004

DO - 10.1038/srep00004

M3 - Article

C2 - 22355523

AN - SCOPUS:80155170088

SN - 2045-2322

VL - 1

JO - Scientific Reports

JF - Scientific Reports

M1 - 4

ER -

Symmetry-breaking dynamical pattern and localization observed in the equilibrium vibrational spectrum of NaI

Abstract

Funding

Access to Document

Other files and links

Fingerprint

Cite this