Li Shi1,Mir Mohammad Sadeghi1,Yajie Huang1,Chao Lian1,Feliciano Giustino1,Emanuel Tutuc1,Allan MacDonald1,Takashi Taniguchi2,Kenji Watanabe3
The University of Texas at Austin1,6National Institute for Materials Science2,National Institute for Materials Science3
Li Shi1,Mir Mohammad Sadeghi1,Yajie Huang1,Chao Lian1,Feliciano Giustino1,Emanuel Tutuc1,Allan MacDonald1,Takashi Taniguchi2,Kenji Watanabe3
The University of Texas at Austin1,6National Institute for Materials Science2,National Institute for Materials Science3
Tunable electron-phonon interaction underpins the ultrahigh mobility, electron hydrodynamics, superconductivity, and superfluidity observed in graphene heterostructures. The electronic thermal conductivity (<i>k</i><i><sub>e</sub></i>) provides unique insight into electron-phonon interaction. Here we report a <i>k</i><i><sub>e</sub></i> measurement that identifies three electron transport regimes in graphene. The measured <i>k</i><i><sub>e</sub></i> of degenerate graphene is suppressed below the Wiedemann-Franz value at temperatures near 30 K by electron-electron interaction and above 120 K by inelastic electron scattering with optical phonons and in-plane polarized acoustic phonons. At intermediate temperatures near 70 K, a breaking of the reflection symmetry in graphene/hexagonal-boron nitride heterostructures enhances quasielastic electron scattering by low-frequency flexural phonons to reduce the mobility and restore the Wiedemann-Franz behavior. The often-neglected flexural phonons play essential roles in charge and heat transport in graphene.