Near-field thermal radiation transfer controlled by plasmons in graphene (1201.1489v3)

Abstract: It is shown that thermally excited plasmon-polariton modes can strongly mediate, enhance and \emph{tune} the near-field radiation transfer between two closely separated graphene sheets. The dependence of near-field heat exchange on doping and electron relaxation time is analyzed in the near infra-red within the framework of fluctuational electrodynamics. The dominant contribution to heat transfer can be controlled to arise from either interband or intraband processes. We predict maximum transfer at low doping and for plasmons in two graphene sheets in resonance, with orders-of-magnitude enhancement (e.g. $10^2$ to $10^3$ for separations between $0.1\mu m$ to $10nm$) over the Stefan-Boltzmann law, known as the far field limit. Strong, tunable, near-field transfer offers the promise of an externally controllable thermal switch as well as a novel hybrid graphene-graphene thermoelectric/thermophotovoltaic energy conversion platform.

Near-field Thermal Radiation Transfer Controlled by Plasmons in Graphene

The paper, "Near-field thermal radiation transfer controlled by plasmons in graphene," focuses on the unique capabilities of graphene in enhancing and controlling thermal radiation at the near-field scale through the excitation of plasmon-polariton modes. The research delineates how these thermally excited plasmon-polariton modes significantly influence, amplify, and tune the near-field radiative heat transfer between closely positioned graphene sheets. This paper assesses the impact of variables such as doping and electron relaxation time on the heat exchange within a near infra-red spectrum, employing the framework of fluctuation electrodynamics.

Several findings emerge as pivotal in this analysis:

1. Plasmon Resonance and Heat Transfer: The investigation reveals that maximum heat transfer occurs at minimal doping levels when plasmons in two graphene sheets are in resonance. The enhancement in heat transfer can be exponentially large, ranging from 10² to 10³ times the conventional Stefan-Boltzmann far-field limit, especially for spacings of 0.1μm to 10nm.
2. Control via Doping and Relaxation Time: The research highlights the capability to manipulate whether heat transfer dominantly arises from interband or intraband processes through control of doping and relaxation time parameters.
3. Efficiency of Plasmonic Graphene: Graphene serves as an optimal material for plasmonic applications due to its tunable plasmon frequencies. These frequencies can situate from terahertz up to the near infra-red, facilitating the thermal excitation of surface modes, unlike conventional metals with higher plasmonic frequencies.

The implications of this research are both practical and theoretical. Practically, the findings suggest potential applications in developing externally controllable thermal switches and innovative energy conversion systems, such as hybrid graphene-graphene thermoelectric or thermophotovoltaic platforms. These systems could advantageously leverage the strong and adjustable near-field heat transfer properties of graphene.

Theoretically, the paper contributes to a deeper understanding of fluctuation electrodynamics and near-field heat transfer phenomena. It emphasizes the role of plasmon-polaritons and opens avenues for exploration into other two-dimensional materials where similar effects might be observed.

Future directions in this research area could involve exploring the behaviors of plasmonic materials under differing environmental conditions or geometries, such as varying temperatures or material substrates. Moreover, integrating graphene with other functional materials could enhance its properties for specific advanced applications in thermal management or energy conversion technologies.

In summary, "Near-field thermal radiation transfer controlled by plasmons in graphene" presents an in-depth analysis of how graphene's unique plasmonic characteristics can revolutionize near-field thermal radiation control and offers a promising outlook for its application in future technological advancements.