Infrared Properties of Hexagonal Silicon Carbide

Spitzer, W. G.; Kleinman, D. A.; Walsh, D.

doi:10.1103/physrev.113.127

Cited by 449 publications

(200 citation statements)

References 26 publications

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“…That is indeed the case, as shown in Fig. 2(c), which shows the force when the substrate has very high losses (ε" = 0.8, high compared to practical ENZ materials, e.g., SiC is a natural ENZ material 23 at around 29 THz where it has ε" ≈ 0.1). We have deliberately chosen an exaggerated imaginary value of ε" = 0.8 to illustrate our point.…”

Section: As a Function Of The Height Over The Substrate (Vertical Aximentioning

confidence: 57%

“…For the Lorentz model of SiC given in Ref 23 , a relatively wide repulsive force fractional bandwidth of 6% around the 29 THz ENZ frequency is obtained. This wide bandwidth is thanks to the broad range of values around ENZ that result in a repulsive force, which resembles conventional repulsion of diamagnetic materials, with permeability  lower than 1, inside an inhomogeneous magnetic field.…”

Section: As a Function Of The Height Over The Substrate (Vertical Aximentioning

confidence: 99%

“…Furthermore, since the expression is frequency independent (aside from the 4 ) / (   h term), we can consider the locus of all points in the (ε', ε'') space that result in a repulsive force, from which we can obtain the associated frequency bandwidth of repulsion for any dispersive ENZ substrate as ε(ω) moves through this region. For the Lorentz model of SiC given in Ref 23 , a relatively wide repulsive force fractional bandwidth of 6% around the 29 THz ENZ frequency is obtained. This wide bandwidth is thanks to the broad range of values around ENZ that result in a repulsive force, which resembles conventional repulsion of diamagnetic materials, with permeability  lower than 1, inside an inhomogeneous magnetic field.…”

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Electric Levitation Usingϵ-Near-Zero Metamaterials

2014

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Levitation of objects with action at a distance has always been intriguing to humans. Several ways to achieve this 1 , such as aerodynamic, acoustic, or electromagnetic methods, including radiation pressure 2 , stable potential wells 3 , and quantum Casimir-Lifshitz forces 4 , exist. A fascinating approach for levitation is that of magnets over superconductors based on the Meissner effect -the expulsion of the magnetic field by a superconductor 5 .With the advent of metamaterials-designed structures with electromagnetic properties that may not be found in nature-we ask whether a material may be conceived exhibiting similar field expulsion, but involving the electric field. We show how a special subcategory of metamaterials, called epsilon-nearzero materials 6-9 , exhibits such electric classic analog to the Meissner effect, exerting a repulsion on nearby sources. Repulsive forces using anisotropic and chiral metamaterials have been investigated 10-16 , but our proposal uses a different mechanism based on field expulsion, and is very robust to both losses and material dispersion. Figure 1 illustrates the basis of our proposal for electric levitation in vicinity of an ENZ metamaterial. Figure 1(a) displays a magnet over a superconducting substrate, demonstrating, in a simple form, the wellknown physics of the Meissner effect. The superconductor expels the magnetic flux density B as it does not allow the flux to penetrate inside. As this is a quantum phenomenon, the superconductor does not simply behave as a perfect conductor, implying only the condition ∂B/∂t = 0, but acts analogous to a perfect diamagnetic material in which B = 0. Although neither of the hypotheses of magnetic permeability μ being zero and conductivity σ → ∞ offers a complete description of the transition into the superconducting state, the phenomenon is occasionally associated 17 with μ = 0-one would expect that a material with μ = 0 expels the magnetic fields away from its surface (since normal component of the magnetic flux density B should be zero outside the material near its surface). This will exert a magnetostatic gradient force on the magnet and levitate the magnet to a stable point. Inspired by this notion, we envision an analogue classical scenario, shown in Fig. 1(b). Can we have an electric classical dual of Meissner effect involving metamaterials? In other words, would an epsilon near zero material (ENZ) exhibit a similar behaviour, albeit classical, for the electric fields? In an ENZ substrate, the displacement current D generated by a polarized particle will be expelled in an analogous (but classic) fashion, and thus may result in levitation of the particle. The apparent simplicity of this analogy may 2 0 10 -7 10 -6 10 -5 -10 -7 -10 -6 -10 -5 be misleading: one could argue that the same analog to Meissner effect could be achieved with the use of a classic conductor, inside which the electric field is zero. However, in such case free charges would accumulate on the surface of a conductor, creating an outside electric field normal...

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Section: As a Function Of The Height Over The Substrate (Vertical Aximentioning

confidence: 57%

Section: As a Function Of The Height Over The Substrate (Vertical Aximentioning

confidence: 99%

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confidence: 99%

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Electric Levitation Usingϵ-Near-Zero Metamaterials

2014

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“…89,90 ε ∞ sets the values at very large energies, and Γ describes the losses in the material. For SiC we use 89,91,92 ω l = 969 cm −1 , ω t = 793 cm −1 , ε ∞ = 6.7, and Γ = 4.76 cm −1 . The frequencies where phononic antenna modes can occur are limited to the window between ω l and ω t , where the real part of ε SiC is negative.…”

Section: ■ Phononic Gap-antennas: Morphology Effects In the Infraredmentioning

confidence: 99%

The Morphology of Narrow Gaps Modifies the Plasmonic Response

et al. 2015

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ABSTRACT:The optical response of a plasmonic gapantenna is mainly determined by the Coulomb interaction of the two constituent arms of the antenna. Using rigorous calculations supported by simple analytical models, we observe how the morphology of a nanometric gap separating two metallic rods dramatically modifies the plasmonic response. In the case of rounded terminations at the gap, a conventional set of bonding modes is found that red-shifts strongly with decreasing separation. However, in the case of flat surfaces, a distinctly different situation is found with the appearance of two sets of modes: (i) strongly radiating longitudinal antenna plasmons (LAPs), which exhibit a red-shift that saturates for very narrow gaps, and (ii) transverse cavity plasmons (TCPs) confined to the gap, which are weakly radiative and strongly dependent on the separation distance between the two arms. The two sets of modes can be independently tuned, providing detailed control of both the near-and far-field response of the antenna. We illustrate these properties also with an application to larger infrared gap-antennas made of polar materials such as SiC. Finally we use the quantum corrected model (QCM) to show that the morphology of the gap has a dramatic influence on the plasmonic response also for subnanometer gaps. This effect can be crucial for the correct interpretation of charge transfer processes in metallic cavities where quantum effects such as electron tunneling are important. KEYWORDS: optical antennas, plasmonic gaps, cavity modes, antenna modes, quantum effects, quantum corrected model, plasmonic resonances, phononic resonances M etallic particles can show a strong optical response due to the excitation of resonant plasmonic modes, making light manipulation possible in structures of dimensions comparable to or smaller than the wavelength. Typical effects are the efficient emission of radiation and the concentration of the incoming light energy in small volumes, thus justifying the characterization of these metallic structures as optical antennas. 1,2 Modifications of the geometry, size, or materials 3−6 affect the optical response. In particular, the resonant modes of optical antennas consisting of two metallic particles separated by a narrow gap show significant sensitivity to the properties of the gap. 7−19 In an optical antenna, a change in geometry can simultaneously affect both the strength and wavelength of its resonances and modify both the far-and near-field response. It is usually a challenge, for example, to control the near field without affecting the far-field properties. In this theoretical work, we discuss how the coexistence 20,21 of two different and mostly spectrally decoupled types of modes in flat-gap antennas, namely, transverse cavity modes 22 and longitudinal antenna modes, 15 allows for a more flexible tuning of far-and near-field properties compared to that of the conventional spherical-gap terminations 13,17,23 The importance of the gap morphology 24 is particularly pronounced for nanometer-...

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“…4: The PPs are placed symmetrically at fixed distance h = 10 −7 m at opposite sides of the sphere's surface, so that their mutual distance is d = 2(R + h). The radius R is varied from 10 −9 m up to 3×10 −5 m. We evaluate expression (17) with temperature T 1 = 300 K, and let the PPs be made of SiC, using the following dielectric function [58]:…”

Section: Heat Transfer In the Presence Of A Sphere Of Arbitrary Sizementioning

confidence: 99%

Heat radiation and transfer for point particles in arbitrary geometries

2017

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We study heat radiation and heat transfer for pointlike particles in a system of other objects. Starting from exact many-body expressions found from scattering theory and fluctuational electrodynamics, we find that transfer and radiation for point particles are given in terms of the Green's function of the system in the absence of the point particles. These general expressions contain no approximation for the surrounding objects. As an application, we compute the heat transfer between two point particles in the presence of a sphere of arbitrary size and show that the transfer is enhanced by several orders of magnitude through the presence of the sphere, depending on the materials. Furthermore, we compute the heat emission of a point particle in front of a planar mirror. Finally, we show that a particle placed inside a spherical mirror cavity does not radiate energy.

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Infrared Properties of Hexagonal Silicon Carbide

Cited by 449 publications

References 26 publications

Electric Levitation Usingϵ-Near-Zero Metamaterials

Electric Levitation Usingϵ-Near-Zero Metamaterials

The Morphology of Narrow Gaps Modifies the Plasmonic Response

Heat radiation and transfer for point particles in arbitrary geometries

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