Accession Number DE2012-1046377
Title Phase Fluctuations and the Absence of Topological Defects in Photo-excited Charge Ordered Nickelate.
Publication Date Jul 2012
Media Count 23p
Personal Author R. G. Moore W. S. Lee Y. Zhu Y. D. Chuang
Abstract 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.
Keywords Amplitudes
Critical temperature
Degrees of freedom
Material properties
Order parameters
X-ray diffraction

Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 71 - Materials Sciences
46 - Physics
Corporate Author Stanford Linear Accelerator Center, CA.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1303
Contract Number DE-AC02-76SF00515

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