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Thermal effects contributing to the Casimir interaction between objects are usually small at room temperature, and they are difficult to separate from quantum mechanical contributions. We propose that the thermal Casimir force effect can be observed for a graphene flake suspended in a fluid between substrates at the room temperature regime. The properly chosen materials for the substrates and fluid induce a Casimir repulsion. The balance with the other forces, such as gravity and buoyancy, results in a stable temperature dependent equilibrium separation. The suspended graphene is a promising system due to its potential for observing thermal Casimir effects at room temperature. [ABSTRACT FROM AUTHOR]

Graphene nanoribbon folds with single and double closed edges are studied using density functional theory methods. The van der Waals dispersive interactions are included via semiempirical pairwise optimized potential. The geometrical phases of the single and double folded ribbons are obtained. The electronic structure in terms of energy needed for the folding process, van der Waals contribution, energy band gaps, and band structures are also calculated. The results are interpreted in terms of peculiarities of the structures and dispersion interactions. It is shown that significant modifications in the electronic structure can be achieved as a result of folding. [ABSTRACT FROM AUTHOR]

The van der Waals dispersion force between graphene nanoribbons is investigated. For this purpose, a nonretarded Lifshitz-like formula for parallel 1D systems is presented within the random phase approximation. Using the response properties of the ribbons from a tight binding model, it is found that the qualitative behavior of the force is similar to the one between two insulating 1D systems. On the other hand, the quantum mechanical van der Waals force can become thermal in nature when the nanoribbons have sufficiently strong chemical potential. It is found that this tuning capability is due to the unique dielectric properties of graphene nanoribbons. Results for other typical 1D materials are also presented, which enable building a better understanding of this ubiquitous force at reduced dimensions. [ABSTRACT FROM AUTHOR]

Dispersion forces, such as Casimir and van der Waals forces, can have a significant influence on the fabrication, handling, and assembly processes as well as the performance of micro- and nanodevices. In this paper, we investigate the Casimir force between a graphene sheet and a ferromagnetic metallic substrate in vacuum. The reflection coefficients, entering the expression for the force, are dependent on the graphene conductivity, which is described by the Kubo formalism. It is found that the magnetic response of the ferromagnet plays a significant role at low temperatures or high value of the graphene chemical potential. The numerical results also demonstrate that the thickness of the metallic plate has a minor influence on the Casimir force. This study maybe useful for the design and operation of micro- and nanodevices. [ABSTRACT FROM AUTHOR]