Anomalous Temperature Induced Transition and Convergence of Thermal Conductivity in Germanene Monolayer

Abstract

We report an anomalous temperature-induced transition in thermal conductivity in germanene monolayer around a critical temperature $T_c=350\text{K}$. Equilibrium molecular dynamics simulations reveal a transition from $\kappa \sim T^{-2}$ scaling below $T_c$ to $\kappa \sim T^{-1/2}$ above, contrasting with conventional $\kappa \sim T^{-1}$ behavior. This anomalous scaling correlates with the long-scale characteristic timescale ${\tau }_2$ obtained from double exponential fitting of the heat current autocorrelation function. Phonon mode analysis using normal mode decomposition indicates that a redshift in ZO phonons reduces the acoustic-optical phonon gap, causing an overlap, enhances the phonon-phonon scattering, driving the anomalous scaling behavior. Moreover, nonequilibrium simulations find a convergent thermal conductivity of germanene with sample size, in agreement with mode coupling theory, owing to the high scattering of ZA phonons due to the inherent buckling of germanene.

To appear in Phys. Chem. Chem. Phys

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Cited by in corpus (1)

• Tunable Interfacial Thermal Conductance in Graphene/Germanene van der Waals Heterostructure using an Optimized Interlayer Potential