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Accession Number
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DE2012-1046377
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Title
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Phase Fluctuations and the Absense of Topological Defects in Photo-excited Charge Ordered Nickelate.
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Publication Date
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Jul 2012
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Media Count
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23p
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Personal Author
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R. G. Moore W. S. Lee Y. Zhu Y. D. Chuang
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Abstract
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The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La(sub 1.75)Sr(sub 0.25)NiO(sub 4) to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.
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Keywords
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Amplitudes
Critical temperature
Defects
Degrees of freedom
Fluctuations
Material properties
Nickelates
Order parameters
Relaxation
Spectroscopy
Topology
X-ray diffraction
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Source Agency
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Technical Information Center Oak Ridge Tennessee
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NTIS Subject Category
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71 - Materials Sciences
46 - Physics
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Corporate Author
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Stanford Linear Accelerator Center, CA.
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Document Type
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Technical report
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Title Note
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N/A
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NTIS Issue Number
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1303
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Contract Number
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DE-AC02-76SF00515
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