Extended Data Fig. 4: The lock-in operation demonstrated with the phenomenological Fourier model.
From: Controllable hydro-thermoelastic heat transport in ultrathin semiconductors at room temperature
a, Temperature dynamics obtained from the diffusive Fourier model using a diffusivity of D = 0.20 cm2/s at two different locations, namely r = 0 and 2 μm from the central hotspot, during square wave modulation (\({f}_{{\rm{mod}}}=10\,{\rm{kHz}}\)) cycles. b, c, Temperature dynamics multiplied by sine (b) and cosine (c) functions. d, Resulting in-phase and out-of-phase spatial profiles after averaging the sine- and cosine-multiplied temperature dynamics at different spatial positions r. e–l, The same results (\({f}_{{\rm{mod}}}=240\,{\rm{kHz}}\)) using a diffusivity of D = 0.20 cm2/s (e–h) and D = 0.02 cm2/s (i–l). l, The in-phase and out-of-phase spatial profiles obtained for D = 0.02 cm2/s, where in-phase profiles show a dip with negative signal a few micrometers away from the central hotspot. The out-of-phase profiles in panels d, h, and l are multiplied by − 1 for convenient comparison.
