nl0c01006_si_005.mov (898.75 kB)
Nanoscale Imaging of Unusual Photoacoustic Waves in Thin Flake VTe2
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posted on 2020-06-09, 19:13 authored by Asuka Nakamura, Takahiro Shimojima, Yusuke Chiashi, Manabu Kamitani, Hideaki Sakai, Shintaro Ishiwata, Han Li, Kyoko IshizakaThe
control of acoustic phonons, which are the carriers of sound
and heat, has become the focus of increasing attention because of
a demand for manipulating the sonic and thermal properties of nanometric
devices. In particular, the photoacoustic effect using ultrafast optical
pulses has a promising potential for the optical manipulation of phonons
in the picosecond time regime. So far, its mechanism has been mostly
based on the commonplace thermoelastic expansion in isotropic media,
which has limited applicability. In this study, we investigate a conceptually
new mechanism of the photoacoustic effect involving a structural instability
that utilizes a transition-metal dichalcogenide VTe2 with
a ribbon-type charge-density-wave (CDW). Ultrafast electron microscope
imaging and diffraction measurements reveal the generation and propagation
of unusual acoustic waves in a nanometric thin plate associated with
optically induced instantaneous CDW dissolution. Our results highlight
the capability of photoinduced structural instabilities as a source
of coherent acoustic waves.
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instabilityUltrafast electron microscope imagingdissolutionmanipulationfocuspulsetransition-metal dichalcogenide VTe 2NanoscaleapplicabilitycapabilityThin Flake VTe 2mechanismgenerationImagingribbon-typecharge-density-waveUnusual Photoacoustic Wavesinstabilitiemediathermoelasticpicosecond time regimemeasurementphotoinduceddemanddevicenanometricCDWdiffractionphotoacoustic effectpropagationphononcarriersourceultrafast
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