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A recent theoretical study computes how electrons in monolayer and bilayer graphene exchange heat with lattice vibrations. The authors build a symmetric heat–current operator and evaluate the non‑equilibrium current–current correlator at finite frequency for unequal electron and phonon temperatures. Analysis yields full analytic expressions in the Bloch–Grüneisen (BG) and equipartition (EP) regimes, and their low‑frequency limits are compared with complete doped intraband on‑shell calculations.
At equilibrium the zero‑frequency noise obeys the thermal fluctuation–dissipation theorem and reproduces established cooling‑power and thermal‑conductance laws. In the BG regime the equilibrium noise scales as |μ| T⁵, while in the EP regime it scales as T⁴ for monolayer graphene and follows a different chemical‑potential dependence for bilayer graphene.
| System and Regime | Cooling law | Gep/A |
|---|
| S(0)/A |
|---|
| MLG BG | ΣMLG(Te4−Tph4) | 4ΣMLGT3 | 8kBΣMLGT5 |
|---|
| MLG EP | gMLG(μ,Te)(Te−Tph) | gMLG(μ,T) | 2kBT2gMLG(μ,T) |
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| BLG BG | ΣBLG(Te4−Tph4) | 4ΣBLGT3 | 8kBΣBLGT5 |
|---|
| BLG EP | gBLG(μ,Te)(Te−Tph) | gBLG(μ,T) | 2kBT2gBLG(μ,T) |
|---|
Finite‑frequency corrections are at the percent level in the upper‑GHz to sub‑THz range for representative graphene parameters. This indicates that for fast thermometry and calorimetric detection, the noise must be evaluated directly rather than inferred from conductance.

The model focuses on clean graphene coupled only to longitudinal acoustic phonons through an unscreened deformation potential. It does not include screening, disorder‑assisted supercollisions, flexural or optical phonons, substrate modes, or interface thermal resistance. The analytical results assume |μ|≫k_B T and that all relevant frequencies remain far below the interlayer hopping energy γ₁, ensuring the validity of the low‑energy bilayer description.
The Bloch–Grüneisen and equipartition expressions are asymptotic limits; a full on‑shell calculation is needed to capture the crossover at intermediate temperatures.