Research Projects

Non-Fourier heat flow regimes such as the hydrodynamic heat flow regime or the second sound offers potential to dissipate heat at speeds comparable to that of sound in modern power-greedy electronics. However, such unconventional heat flow regimes have only been experimentally realized in graphite till now. In this proposal, we intend to explore the possibility of realizing such intriguing heat flow regimes beyond textbook Fourier's law in stacked and twisted hetero-structures with the two-dimensional monolayers of common van der Walls semiconductors as building blocks. First, we will utilize the recently-developed low-rank solution of the governing equation for phonon transport - the linearized Peierls-Boltzmann equation (LPBE) to predict the ingredients of the hetero-structures that can host hydrodynamic heat flow. Second, we will fabricate these hetero-structures using exfoliation techniques from commercially-available bulk materials and stack and twist them using a set-up incorporated within a custom microscope, and third - we will perform optical pump-probe measurements using a transient grating set-up in our lab by taking advantage of the unconventional electronic structure in many of the two-dimensional hetero-structures that facilitate exceptional laser absorption within a few atomic layers of thickness. Our work will drive design and development of next-generation semiconductor electronics with this new kind of heat dissipation mechanism beyond textbook Fourier's law at the core.