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arXiv · 1807.03670

Early-stage dynamics of metallic droplets embedded in the nanotextured Mott insulating phase of V$_2$O$_3$

Andrea Ronchi·Pía Homm·Mariela Menghini·Paolo Franceschini·Francesco Maccherozzi·Francesco Banfi·Gabriele Ferrini·Federico Cilento·Fulvio Parmigiani·Sarnjeet S. Dhesi·Michele Fabrizio·Jean-Pierre Locquet·Claudio Giannetti
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Abstract

Unveiling the physics that governs the intertwining between the nanoscale self-organization and the dynamics of insulator-to-metal transitions (\textit{IMT}) is key for controlling on demand the ultrafast switching in strongly correlated materials and nano-devices. A paradigmatic case is the \textit{IMT} in V$_2$O$_3$, for which the mechanism that leads to the nucleation and growth of metallic nano-droplets out of the supposedly homogeneous Mott insulating phase is still a mystery. Here, we combine X-ray photoemission electron microscopy and ultrafast non-equilibrium optical spectroscopy to investigate the early stage dynamics of isolated metallic nano-droplets across the \textit{IMT} in V$_2$O$_3$ thin films. Our experiments show that the low-temperature monoclinic antiferromagnetic insulating phase is characterized by the spontaneous formation of striped polydomains, with different lattice distortions. The insulating domain boundaries accommodate the birth of metallic nano-droplets, whose non-equilibrium expansion can be triggered by the photo-induced change of the 3$d$-orbital occupation. We address the relation between the spontaneous nanotexture of the Mott insulating phase in V$_2$O$_3$ and the timescale of the metallic seeds growth. We speculate that the photoinduced metallic growth can proceed along a non-thermal pathway in which the monoclinic lattice symmetry of the insulating phase is partially retained.

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Andrea Ronchi, Pía Homm, Mariela Menghini, Paolo Franceschini, Francesco Maccherozzi, Francesco Banfi, Gabriele Ferrini, Federico Cilento, Fulvio Parmigiani, Sarnjeet S. Dhesi, Michele Fabrizio, Jean-Pierre Locquet, Claudio Giannetti. 2018-07-10. Early-stage dynamics of metallic droplets embedded in the nanotextured Mott insulating phase of V$_2$O$_3$. https://doi.org/10.1103/physrevb.100.075111

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