Spatially confined low-power optically pumped ultrafast synchrotron x-ray nanodiffraction

Park, Joonkyu; Zhang, Qingteng; Chen, Pice; Cosgriff, Margaret P.; Tilka, Jack A.; Adamo, Carolina; Schlom, Darrell G.; Wen, Haidan; Zhu, Yi; Evans, Paul G.

doi:10.1063/1.4929436

Cited by 7 publications

(6 citation statements)

References 25 publications

(38 reference statements)

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“…Focused X‐ray diffraction (nano‐XRD) is an important methodology in crystallography research due to its high spatial resolution, typically at the micrometer scale or lower. Nano‐XRD achieves this high resolution by focusing X‐rays with a Fresnel zone plate or a Kirpatrick‐Baez mirror . State‐of‐the‐art nano‐XRD techniques can currently reach a resolution of 30 nm, comparable to the resolution of s‐SNOM.…”

Section: Current Stagementioning

confidence: 99%

Modern Scattering‐Type Scanning Near‐Field Optical Microscopy for Advanced Material Research

et al. 2019

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IntroductionOver the past decade, optical near-field techniques, especially scattering-type scanning near-field optical microscopy Infrared and optical spectroscopy represents one of the most informative methods in advanced materials research. As an important branch of modern optical techniques that has blossomed in the past decade, scattering-type scanning near-field optical microscopy (s-SNOM) promises deterministic characterization of optical properties over a broad spectral range at the nanoscale. It allows ultrabroadband optical (0.5-3000 µm) nanoimaging, and nanospectroscopy with fine spatial (<10 nm), spectral (<1 cm −1 ), and temporal (<10 fs) resolution. The history of s-SNOM is briefly introduced and recent advances which broaden the horizons of this technique in novel material research are summarized. In particular, this includes the pioneering efforts to study the nanoscale electrodynamic properties of plasmonic metamaterials, strongly correlated quantum materials, and polaritonic systems at room or cryogenic temperatures. Technical details, theoretical modeling, and new experimental methods are also discussed extensively, aiming to identify clear technology trends and unsolved challenges in this exciting field of research. and Astronomy. His research interests cover nanoscale and ultrafast electromagnetic responses of strongly correlated electron materials, 2D materials, and metamaterials that span from the near-infrared to terahertz frequencies.tip-sample interactions. In s-SNOM, these difficulties result from at least three factors. First, the well-known antenna effect [48] causes light to be highly confined between the probe apex and the sample surface. The specific geometry of the tip shank plays a significant role in determining the intensity of the scattered signal. [49] Second, in addition to the local optical information, a strong but undesired background signal can be detected. This background signal can be mainly attributed to the light scattering from the tip shank, cantilever, and sample surface. Third, due to the broad momentum distribution of the localized radiation, in some cases, nominally "far-field trivial" Adv. Mater. 2019, 31, 1804774 Figure 1. Far-field (blue) and near-field (yellow) measurements, accessing the propagating field and the evanescent field, respectively.The authors declare no conflict of interest.

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Section: Current Stagementioning

confidence: 99%

Modern Scattering‐Type Scanning Near‐Field Optical Microscopy for Advanced Material Research

et al. 2019

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“…Since the recovery time as shown below is longer than the interval between pump pulses, the optical excitation can be regarded as a quasi-continuous and the results reported here are given in terms of time-average intensity. Optical pulses were transported to the sample stage using a multi-mode optical fiber and focused with an ultraviolet objective lens to allow spatial overlap with the x-ray beam [31]. The optical focus had approximately a Gaussian spatial profile with full-width-at-half maximum (FWHM) diameter of 110 µm.…”

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Photoinduced Domain Pattern Transformation in Ferroelectric-Dielectric Superlattices

et al. 2017

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The nanodomain pattern in ferroelectric/dielectric superlattices transforms to a uniform polarization state under above-bandgap optical excitation. X-ray scattering reveals a disappearance of domain diffuse scattering and an expansion of the lattice. The reappearance of the domain pattern occurs over a period of seconds at room temperature, suggesting a transformation mechanism in which charge carriers in long-lived trap states screen the depolarization field. A Landau-Ginzburg-Devonshire model predicts changes in lattice parameter and a critical carrier concentration for the transformation.

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“…Using a newly developed laser pumped x-ray diffraction imaging technique with 350 nm spatial resolution and 100 ps temporal resolution 39 , we quantitatively studied the structural phase propagation during the photo-induced phase transition in a VO 2 thin film ( Fig. 1a ).…”

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Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

Zhu

Cai

Chen

et al. 2016

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Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

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Spatially confined low-power optically pumped ultrafast synchrotron x-ray nanodiffraction

Cited by 7 publications

References 25 publications

Modern Scattering‐Type Scanning Near‐Field Optical Microscopy for Advanced Material Research

Modern Scattering‐Type Scanning Near‐Field Optical Microscopy for Advanced Material Research

Photoinduced Domain Pattern Transformation in Ferroelectric-Dielectric Superlattices

Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

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