Enhanced hot luminescence at van Hove singularities in twisted bilayer graphene

Summary form only given. In twisted bilayer graphene (tBLG), the electronic and optical properties show interesting dependence on the interlayer rotation angle(0) with promising device applications [1,2]. The presence of the van Hove singularities in the density of states leads to an enhancement of the optical absorption at energies that depends on the rotation angle [2]. In single layer graphene, it has been shown that after excitation with a femtosecond pulse the excited carriers forms a quasi-equilibrium population at temperatures well above the lattice temperature that leads to thermal like emission, i.e. hot luminescence [3]. Here, we report on hot luminescence measurements with femtosecond laser pulse excitation on tBLG that shows an enhancement of the light emission as the excitation wavelength is tuned to a van Hove singularity resonance energy.Γ