Abstract
The ability to transport energy is a fundamental property of the two-dimensional Dirac fermions in graphene. Electronic thermal transport in this system is relatively unexplored and is expected to show unique fundamental properties and to play an important role in future applications of graphene, including optoelectronics, plasmonics, and ultrasensitive bolometry. Here, we present measurements of bipolar thermal conductances due to electron diffusion and electron-phonon coupling and infer the electronic specific heat, with a minimum value of 10k_B (10^(−22) J/K) per square micron. We test the validity of the Wiedemann-Franz law and find that the Lorenz number equals 1.32×(π^2/3)(kB/^e)^2. The electron-phonon thermal conductance has a temperature power law T^2 at high doping levels, and the coupling parameter is consistent with recent theory, indicating its enhancement by impurity scattering. We demonstrate control of the thermal conductance by electrical gating and by suppressing the diffusion channel using NbTiN superconducting electrodes, which sets the stage for future graphene-based single-microwave photon detection.
Highlights
Electrical transport in graphene has attracted much attention because of the pseudochiral and relativistic nature of the band structure [1,2]
The ability to transport energy is a fundamental property of the two-dimensional Dirac fermions in graphene
Since both electrons and holes carry energy as well as charge, the thermal transport of Dirac fermions in two dimensions is expected to be as fascinating as its electrical counterpart
Summary
Electrical transport in graphene has attracted much attention because of the pseudochiral and relativistic nature of the band structure [1,2]. Since both electrons and holes carry energy as well as charge, the thermal transport of Dirac fermions in two dimensions is expected to be as fascinating as its electrical counterpart. Previous thermal studies of graphene have been limited to measurements of thermoelectric power [21,22,23] or to measurements of thermal conductance taken at temperatures above the Bloch-Gruneisen (BG) temperature [24,25], at the charge neutrality point (CNP) [11], or without considering the effects of disorder [26]. Significant discrepancies between the theoretical [17,18,19,20] and measured values [26] of both the ep coupling temperature power law and the coupling constant are found in some of these experiments
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