Ajit K. Vallabhaneni

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We show that thermal rectification (TR) in asymmetric graphene nanoribbons (GNRs) is originated from phonon confinement in the lateral dimension, which is a fundamentally new mechanism different from that in macroscopic heterojunctions. Our molecular dynamics simulations reveal that, though TR is significant in nanosized asymmetric GNRs, it diminishes at(More)
Using classical molecular dynamics simulation, we have studied the effect of edge-passivation by hydrogen ͑H-passivation͒ and isotope mixture ͑with random or superlattice distributions͒ on the thermal conductivity of rectangular graphene nanoribbons ͑GNRs͒ ͑of several nanometers in size͒. We find that the thermal conductivity is considerably reduced by the(More)
We employ classical molecular dynamics to study the nonlinear thermal transport in graphene nanoribbons (GNRs). For GNRs under large temperature biases beyond linear response regime, we have observed the onset of negative differential thermal conductance (NDTC). NDTC is tunable by varying the manner of applying the temperature biases. NDTC is reduced and(More)
This work examines the quality factors (Q factors) of resonance associated with the axial and transverse vibrations of single-wall carbon nanotube (SWCNT) resonators through the use of molecular dynamics (MD) simulation. Specifically, the work investigates the effect of device length, diameter, and chirality, as well as temperature, on the resonant(More)
This article reviews recent numerical studies of thermal transport in graphene, with a focus on molecular dynamics simulation, the atomistic Green's function method, and the phonon Boltzmann transport equation method. The mode-wise phonon contribution to the intrinsic thermal conductivity (κ) of graphene and the effects of extrinsic mechanisms—for example,(More)
Various models were previously used to predict interfacial thermal conductance of vertical carbon nanotube (CNT)-silicon interfaces, but the predicted values were several orders of magnitude off the experimental data. In this work, we show that the CNT filling fraction (the ratio of contact area to the surface area of the substrate) is the key to remedy(More)
The measured frequencies and intensities of different first- and second-order Raman peaks of suspended graphene are used to show that optical phonons and different acoustic phonon polarizations are driven out of local equilibrium inside a submicron laser spot. The experimental results are correlated with a first-principles-based multiple temperature model(More)
This work examines the impact of defects on the resonant response of single-wall carbon nanotube (CNT) resonators using classical molecular dynamics (MD) simulations. The work demonstrates that the presence of defects in CNTs leads to appreciable resonant mode splitting. A dimensionless parameter has been introduced to quantify this phenomenon. It is(More)
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