Fig. 1: Spatiotemporally mapped heat transport in MoSe2 crystals.
From: Controllable hydro-thermoelastic heat transport in ultrathin semiconductors at room temperature
a, Optical images of suspended MoSe2 samples with the thickness given in the number of layers L. b, Concept of a spatiotemporal thermometry experiment in which a train of ultrafast pump pulses (green) creates a local hotspot in the centre of a suspended thin film. By spatially scanning a train of ultrafast probe pulses (purple) across the suspended region, arriving with a pump–probe delay time of ~13 ns, we directly track how in-plane heat flow occurs in space and time. c,d, In-phase (filled circles) and out-of-phase (open circles) transient reflectivity profiles ΔR/R(r), normalized to the peak of the fit of the in-phase signal, measured on an ~15-layer-thick (c) and 1-layer-thick (d) MoSe2 flake. The dashed and solid blue lines correspond to a simulation of purely diffusive heat transport according to Fourier’s law with the ‘effective diffusivity’ as an adjustable parameter (see the ‘Phenomenological diffusive Fourier model’ section). norm., normalized.
