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Two-dimensional ferroelectric materials like NbOI have garnered significant interest, yet their temporal response and synergetic interaction with light remain underexplored. Previous studies on the polarization of oxide ferroelectrics have relied on time-resolved optical second harmonic generation or ultrafast X-ray scattering. Here, we probe the laser-induced polarization dynamics of NbOI nanocrystals using ultrafast transmission electron diffraction and deflectometry. The deflection of the electron pulses is directly sensitive to the changes in the polarization, while the diffraction signal captures the structural evolution. Excited with a UV laser pulse, the polarization of NbOI is initially suppressed for two picoseconds, then it recovers and overshoots, leading to a transiently enhanced polarization persisting for over 200 ps. This recovery coincides with coherent acoustic phonon generation, triggering a piezoresponse in the NbOI nanocrystals. Our results offer a new method for sensing the ferroelectric order parameter on femtosecond time scales.
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http://dx.doi.org/10.1038/s41467-025-63533-9 | DOI Listing |
Nano Lett
September 2025
Department of Physics and Astronomy, University of Nebraska─Lincoln, Lincoln, Nebraska 68588, United States.
In this study, using a set of scanning probe microscopy techniques, we investigate the electronic properties of the domain walls in the layered ferroelectric semiconductor of the transition metal oxide dihalide family, NbOI. Although the uniaxial ferroelectricity of NbOI allows only 180° domain walls, the pristine 2D flakes, where polarization is aligned in-plane, typically exhibit a variety of as-grown domain patterns outlined by the electrically neutral and charged domain walls. The electrically biased probing tip can modify the as-grown domain structures.
View Article and Find Full Text PDFNat Commun
August 2025
Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE, USA.
Two-dimensional ferroelectric materials like NbOI have garnered significant interest, yet their temporal response and synergetic interaction with light remain underexplored. Previous studies on the polarization of oxide ferroelectrics have relied on time-resolved optical second harmonic generation or ultrafast X-ray scattering. Here, we probe the laser-induced polarization dynamics of NbOI nanocrystals using ultrafast transmission electron diffraction and deflectometry.
View Article and Find Full Text PDFACS Nano
August 2025
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, Liaoning 116024, China.
Two-dimensional (2D) layered ferroelectrics, as an emerging area of research, have attracted extensive attention, while memristors based on 2D ferroelectric materials are yet to be fully explored, thereby limiting their applications in modern nanoelectronics. In this work, we report the observation of intrinsic memristive behavior in a recently discovered 2D in-plane ferroelectric material, NbOI, and the giant enhancement of the memristive performance by using light-emission diode (LED) visible light. The results show that NbOI devices exhibit an intrinsically strong memristive response with a current on/off ratio of up to 10 and stable switching cycles, which is largely independent of the back-gate voltage.
View Article and Find Full Text PDFAdv Mater
August 2025
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.
High-dynamic-range (HDR) visual environments, where extremely bright and dark regions coexist, pose major challenges for conventional imaging systems that rely on multi-frame exposure fusion and cloud-based post-processing. These approaches often suffer from high latency, limited efficiency, and privacy concerns, making them unsuitable for real-time or edge-level intelligent vision. Here, a 2D Time-Stretching Anisotropic Synapse (2D TSAS) is reported that enables in-sensor intensity-spanning feature fusion from a single image frame.
View Article and Find Full Text PDFNano Lett
January 2025
Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China.
Two-dimensional ferroelectric materials can generate a bulk photovoltaic effect, making them highly promising for self-powered photodetectors. However, their practical application is limited by a weak photoresponse due to a weak transition strength and wide band gap. In this study, we construct a van der Waals heterojunction using NbOI, which has significant in-plane polarization, with a highly absorbing MoSe layer.
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