Energy Loss Rates in Carbonic Materials: Carbon Nanotubes and Hydrogen Intercalated Bilayer Graphene

This thesis consists of two parts. In the first part, we simulate the energy transfer rate from hot electrons to phonons using the two-temperature model, which occurs through electron–phonon interactions in Double-Walled Carbon Nanotubes (DWCNTs). In the second part, we investigate the damping of Shubnikov-de Haas (SdH) oscillations in response to external stimuli. In the first part, the coupling constant in DWCNTs was verified by simulating the temporal temperature profile using the Two-Temperature Model (TTM). The simulations were implemented in Python with the NTMpy package, yielding a coupling constant of (2.3 $10^{16}$ W/$m^3$). The computational framework employs the Transfer Matrix Method to solve the boundary value problem and the Explicit Euler Method for the initial value problem. The simulation allows users to define boundary conditions (Dirichlet or Neumann) and to modify both the polarization and temporal profile of the incident light source. Three subsystems are considered—the electronic, electronic spin, and lattice systems—but the spin subsystem is neglected due to the ultrafast timescales involved, which render its contribution negligible. To validate the model, the source term was adjusted so that the simulated electronic temperature matched the experimental measurements. The second part of the thesis presents an experimental investigation of SdH oscillation damping. A Van der Pauw sample was subjected to a perpendicular magnetic field to induce longitudinal resistivity oscillations. By sweeping the magnetic field and varying the ambient temperature, the temperature-dependent damping of the SdH amplitude was observed. The damping behavior of the oscillations was analyzed using the Lifshitz–Kosevich formula to extract the charge carrier temperature, which was found to range from 1.68 K to 2.5 K. The oscillation frequencies were observed between 1.3 to 2.1×$10^{13} s^{-1}$, allowing us to estimate the effective mass of the electrons, which was approximately 1.4 times larger than that of bilayer graphene without hydrogen intercalation. However, due to experimental limitations, the energy loss rate per charge carrier could not be determined.