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arXiv · 1706.00616

Subcycle insulator-to-metal transition in vanadium dioxide by terahertz-field-driven tunneling

Flavio Giorgianni·Carlo Vicario·Mostafa Shalaby·Junqiao Wu·Kai Liu·Kevin Wang·Christoph P. Hauri
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Abstract

In vanadium dioxide, the interplay between coherent lattice transformation and electronic correlation drives an insulator-to-metal transition (IMT). This phase commutation can be triggered by temperature, pressure, doping or deposition of optical energy. Here we demonstrate that an atomically-strong terahertz electric field initiates a metastable ultrafast IMT in vanadium dioxide without a concomitant lattice transformation. The free-space terahertz field acts as off-resonant excitation with photon energy below the lattice phonons and the interband transitions. Differently from optical and infrared excitation, terahertz interaction leads to a full IMT by interband Zener tunneling with a negligible entropy deposition. In previous experiments the temporal dynamics of IMT in VO2 could be only indirectly inferred. We disentangle the electronic and lattice contributions to the IMT on a sub-picosecond timescale. Near the critical temperature the IMT becomes dissipative and the terahertz field concludes the lattice-assisted metallic nucleation initiated by heating. The method of strong-field induced phase transition presented here is applicable to a wide class of strongly correlated systems and will enable the discovery of novel metastable phases.

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Flavio Giorgianni, Carlo Vicario, Mostafa Shalaby, Junqiao Wu, Kai Liu, Kevin Wang, Christoph P. Hauri. 2017-09-01. Subcycle insulator-to-metal transition in vanadium dioxide by terahertz-field-driven tunneling. https://arxiv.org/abs/1706.00616

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