Managing heat efficiently is one of the great challenges in the development of next-generation electronic and optoelectronic devices. At the nanoscale, energy moves in ways that defy classical descriptions of heat transfer. Houssem Rezgui, researcher from the Sotomayor research group at INL, has now provided new insights into how energy flows in graphene when excited with ultrafast laser pulses. Their work, published as a Letter in Journal of Physics D: Applied Physics, explores how electrons and vibrations in the lattice (known as phonons) interact in timeframes shorter than a trillionth of a second. Graphene, with its remarkable electronic and thermal properties, is an ideal platform for probing these processes. When struck by a femtosecond laser pulse, graphene enters a highly non-equilibrium state: electrons absorb the incoming energy almost instantly, and only afterward begin to share it with the lattice. Traditionally, this sequence has been described by the two-temperature model, which assumes that electrons and phonons equilibrate in a straightforward way. However, the INL researcher shows that reality is more complex. Using an extended temperature model, Rezgui revealed that different phonon branches respond at distinct timescales, with longitudinal acoustic phonons playing a key role in energy absorption and redistribution. Strikingly, their […]
Read more
