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Ultrafast insulator-metal transition in VO2 nanostructures assisted by picosecond strain pulses

Mogunov, Ia. A.; Fernández, F.; Lysenko, S.; Kent, A.J.; Scherbakov, A.V.; Kalashnikova, A.M.; Akimov, A.V.

Ultrafast insulator-metal transition in VO2 nanostructures assisted by picosecond strain pulses Thumbnail


Authors

Ia. A. Mogunov

F. Fernández

S. Lysenko

ANTHONY KENT anthony.kent@nottingham.ac.uk
Professor of Physics

A.V. Scherbakov

A.M. Kalashnikova

ANDREY AKIMOV ANDREY.AKIMOV@NOTTINGHAM.AC.UK
Principal Research Fellow



Abstract

Strain engineering is a powerful technology that exploits the stationary external or internal stress of specific spatial distribution for controlling the fundamental properties of condensed materials and nanostructures. This advanced technique modulates in space the carrier density and mobility, the optical absorption, and in strongly correlated systems, the phase, e.g., insulator-metal or ferromagnetic-paramagnetic. However, while successfully accessing nanometer-length scales, strain engineering is yet to be brought down to ultrafast time scales allowing strain-assisted control of the state of matter at THz frequencies. We demonstrate control of an optically-driven insulator-to-metal phase transition by a picosecond strain pulse, which paves the way to ultrafast strain engineering in nanostructures with phase transitions. This is realized by simultaneous excitation of VO2 nanohillocks by a 170-fs laser and picosecond strain pulses finely timed with each other. By monitoring the transient optical reflectivity of the VO2, we show that strain pulses, depending on the sign of the strain at the moment of optical excitation, increase or decrease the fraction of VO2 that undergoes an ultrafast phase transition. A transient strain of moderate amplitude of approximately 0.1% applied during ultrafast photo-induced nonthermal transition changes the fraction of VO2 in the laser-induced phase by approximately 1%. In contrast, if applied after the photoexcitation when the phase transformations of the material are governed by thermal processes, a transient strain of the same amplitude produces no measurable effect on the phase state.

Journal Article Type Article
Acceptance Date Dec 22, 2018
Online Publication Date Jan 28, 2019
Publication Date Jan 28, 2019
Deposit Date Feb 14, 2019
Publicly Available Date Feb 14, 2019
Journal Physical Review Applied
Electronic ISSN 2331-7019
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 11
Issue 1
Article Number 014054
DOI https://doi.org/10.1103/physrevapplied.11.014054
Public URL https://nottingham-repository.worktribe.com/output/1549272
Publisher URL https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.11.014054

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