Jun 16 – 20, 2024
Clarion Hotel Sea U, Helsingborg
Europe/Stockholm timezone

Coherent Correlation Imaging for resolving fluctuating states of matter

Jun 17, 2024, 2:35 PM
20m
Clarion Hotel Sea U, Helsingborg

Clarion Hotel Sea U, Helsingborg

Speaker

Christopher Klose (Max Born Institute Berlin)

Description

Fluctuations and stochastic processes are ubiquitous in nanometer-scale systems, especially in the presence of disorder. Real-space access to fluctuating states is impeded by a fundamental dilemma between spatial and temporal resolution. Averaging over an extended period of time (or repetitions) is key for the majority of high-resolution imaging experiments, especially in weak contrast systems. If, by lack of better knowledge, averaging is indiscriminate, it leads to a loss of temporal resolution and to motion-blurred images.
We present coherent correlation imaging (CCI) [1] – a high-resolution, full-field imaging technique that realizes multi-shot, time-resolved imaging of stochastic processes. The key idea of CCI is the classification of Fourier-space coherent scattering images based on the speckle fingerprints of the real-space state – even at a low photon count where imaging is not possible. Contrast and spatial resolution emerge by averaging selectively over same-state frames. Temporal resolution down to the acquisition time of single frames arises independently from an exceptionally low misclassification rate, which we achieve by combining correlation-based similarity metric with powerful classification algorithm.
We apply CCI to study previously inaccessible magnetic fluctuations in a highly degenerate magnetic stripe domain state with nanometer-scale resolution. Our material is a Co-based chiral ferromagnetic multilayer with magnetic pinning low enough to exhibit stochastically recurring dynamics that resemble thermally-induced Barkhausen jumps near room temperature. CCI reconstructs high-resolution real-space images of all domain states by holographically aided phase retrieval [2, 3] and, unlike previous approaches, also tracks the time when these states occur. The spatiotemporal imaging reveals an intrinsic transition network between the states and unprecedented details of the magnetic pinning landscape allowing us to explain the dynamics on a microscopic level.
CCI massively expands the potential of emerging high-coherence X-ray sources and paves the way for addressing large fundamental questions such as the contribution of pinning and topology in phase transitions and the role of spin and charge order fluctuations in high-temperature superconductivity.

[1] C. Klose et. al., Coherent correlation imaging for resolving fluctuating states of matter. Nature 614, 256-261 (2023)
[2] S. Zayko et al., Ultrafast high-harmonic nanoscopy of magnetization dynamics. Nat. Commun. 12, 6337 (2021).
[3] R. Battistelli, et. al., Coherent x-ray magnetic imaging with 5 nm resolution, Optica, DOI 10.1364/OPTICA.505999

Primary authors

Christopher Klose (Max Born Institute Berlin) Felix Büttner (Helmholtz-Zentrum für Materialien und Energie Berlin) Wen Hu (Brookhaven National Laboratory) Mazzoli Claudio (Brookhaven National Laboratory) Kai Litzius (Massachusetts Institute of Technology) Riccardo Battistelli (Helmholtz-Zentrum für Materialien und Energie Berlin) Sergey Zayko (University of Göttingen) Ivan Lemesh (Massachusetts Institute of Technology) Jason M. Bartell Mantao Huang (Massachusetts Institute of Technology) Christian M. Günther (Technische Universität Berlin) Michael Schneider (Max Born Institute Berlin) Andi Barbour (Brookhaven National Laboratory) Stuart B. Wilkins (Brookhaven National Laboratory) Geoffrey S. D. Beach (Massachusetts Institute of Technology) Stefan Eisebitt (Max Born Institute Berlin) Bastian Pfau (Max Born Institute Berlin)

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