Singular resonance in fluctuation-electromagnetic phenomena during the rotation of a nanoparticle near a surface

It is shown that in fluctuation-electromagnetic phenomena (Casimir force, Casimir friction, radiative heat generation) for a spherical nanoparticle with a radius $R$ rotating near a surface a singular resonance can occur, near which fluctuation-electromagnetic effects are strongly enhanced even in the presence of dissipation in the system. The resonance takes place at the particle-surface separation $d <d_0= R[3/4\varepsilon_1''(\omega_1)\varepsilon_2''(\omega_2)]^{1/3}$ (where $\varepsilon_i''(\omega_i)$ is the imaginary part of the dielectric function of a particle or a medium at the surface plasmon or phonon polariton frequency $\omega_i$), when the rotation frequency $\Omega$ coincides with the poles in the photon generation rate at $\Omega\approx \omega_1 + \omega_2$. These poles arise due to the multiple scattering of electromagnetic waves between the particle and the surface under the conditions of the anomalous Doppler effect and they exist even in the presence of dissipation. For $d <d_0$ in the dependence on the particle rotation frequency the Casimir force can change sign, i.e. the attraction of the particle to the surface is replaced by the repulsion. The obtained results can be important for nanotechnology.Comment: 8 pages, 2 figure

Resonant photon tunneling enhancement of the van der Waals friction

We study the van der Waals friction between two flat metal surfaces in relative motion. For good conductors we find that normal relative motion gives a much larger friction than for parallel relative motion. The friction may increase by many order of magnitude when the surfaces are covered by adsorbates, or can support low-frequency surface plasmons. In this case the friction is determined by resonant photon tunneling between adsorbate vibrational modes, or surface plasmon modes.Comment: Published in PR

Resonant photon tunneling enhancement of the radiative heat transfer

We study the dependence of the heat transfer between two semi-infinite solids on the dielectric properties of the bodies. We show that the heat transfer at short separation between the solids may increase by many order of magnitude when the surfaces are covered by adsorbates, or can support low-frequency surface plasmons. In this case the heat transfer is determined by resonant photon tunneling between adsorbate vibrational modes, or surface plasmon modes. We study the dependence of the heat flux between two metal surfaces on the electron concentration using the non-local optic dielectric approach, and co mpare with the results obtained within local optic approximation.Comment: 5 pages, 3 figure

Non-contact friction between nanostructures

We calculate the van der Waals friction between two semi-infinite solids in normal relative motion and find a drastic difference in comparison with the parallel relative motion. The case of the good conductors is investigated in details both within the local optic approximation, and using a non-local optic dielectric approach. We show that the friction may increase by many order of magnitude when the surfaces are covered by adsorbates, or can support low-frequency surface plasmons. In this case the friction is determined by resonant photon tunneling between adsorbate vibrational modes, or surface plasmon modes. The theory is compared to atomic force microscope experimental data.Comment: Published in PR

Influence of electric current on the Casimir forces between graphene sheets

We investigate the dependence of the thermal Casimir force between two graphene sheets on the drift velocity of the electrons in one graphene sheet. We show that the drift motion produces a measurable change of the thermal Casimir force due to the Doppler effect. The thermal Casimir force as well as the Casimir friction are strongly enhanced in the case of resonant photon tunneling when the energy of the emitted photon coincides with the energy of electron-hole pair excitations. In the case of resonant photon tunneling, even for temperatures above room temperature the Casimir friction is dominated by quantum friction due to quantum fluctuations. Quantum friction can be detected in frictional drag experiment between graphene sheets for high electric field.Comment: 6 pages, 2 figure