Plasmons in 2D materials

We study plasmons in the 2D materials graphene, MoS2 and black phosphorous using the local and the non-local RPA conductivity. These three materials are respectively zero-gap, large gap and anistropic 2D materials, thus... [ view full abstract ]

We study plasmons in the 2D materials graphene, MoS2 and black phosphorous using the local and the non-local RPA conductivity. These three materials are respectively zero-gap, large gap and anistropic 2D materials, thus representing a broad variety of 2D materials. Non-local effects are known to be important in applications involving large in-plane wavevector components, such as the enhancement of the dipole radiation rate (Purcell factor) in the vicinity of a lossy material, and in calculations of the lifetime of excited electrons. We investigate the importance of non-local effects and the importance of resonant plasmon modes for the Purcell factor. Furthermore we present calculations of plasmon dispersions in a pump-probe setup where the local electron temperature can easily reach several thousands Kelvin. In this setup plasmons are activated by locally increasing the temperature using an intense laser beam and subsequently the response is measured using a second laser. We provide calculations of Purcell factors for the three materials in this scenario, as well as calculations of the electron lifetime, a measure which is highly relevant in a pump-probe experiment. Finally, we calculate for all materials the equivalent temperature for a given Fermi level, to study the difference between thermal doping and electron doping.