The effective medium approximations: Some recent developments

Stroud, D.

doi:10.1006/spmi.1997.0524

Cited by 218 publications

(117 citation statements)

References 10 publications

Supporting

Mentioning

109

Contrasting

Unclassified

Order By: Relevance

“…We account for the surface roughness of samples 2, 3, and 4 by assuming that the top 6 nm of the film, the thickness of which is consistent with the measurement by atomic force microscopy, to have a gold fill fraction of 0.5. One sees that the results of the calculation agree reasonably well with the experimental results, which demonstrates the qualitative validity of the EMA model [16,17]. With more knowledge about the geometry of the nanograins of the nanocomposite one could use more advanced effective medium theories [16,18,19] to calculate ជ eff more accurately.…”

supporting

confidence: 60%

Surface-plasmon polaritons on metal-dielectric nanocomposite films

et al. 2009

View full text Add to dashboard Cite

We observe experimentally that the reflectances of metal-dielectric nanocomposite films in the Kretschmann configuration show different characteristics, depending on the metal fill fraction f, that fall into one of three distinct regimes. In the "metallic" regime, in which f is large, the film supports conventional surface-plasmon polaritons (SPPs), and one can tailor the properties of the SPPs by controlling the value of f. In the "dielectric" regime, in which f is small, the film does not support any surface modes. In the intermediate "lossy" regime, the nanocomposite film supports a SPP mode that is different from that of a "metallic" film. These results are explained by using an anisotropic effective medium model and mode analysis. [5][6][7]. It has been shown that the properties of SPPs can be tailored by the use of artificially synthesized periodic or random metaldielectric nanocomposite materials [8][9][10]. Yet most of these studies assume that the metal in the nanocomposite is interconnected. In this Letter, we investigate how the properties of SPPs supported by random nanocomposite films evolve as the metal fill fraction is varied. Specifically, we explore the transition from continuous metal films to semicontinuous films to isolated nanoislands. We fabricated a large collection of gold-air nanocomposite films with gold fill fractions f ranging from 1 to approximately 0.3. All samples are approximately 30 nm thick. The pure gold films were fabricated by using electron-beam evaporation, the films with high values of f were fabricated by using sputter coating, and those with moderate values of f were fabricated by using the pulsed laser deposition method [11]. We measured the reflectances of these nanocomposite films as functions of the incidence angle in glass inc in the Kretschmann configuration at the wavelength of 1550 nm (see Fig. 1). The measured reflectance is calibrated with that from a bare prism under the same conditions to exclude the influence of unrelated interfaces. Five representative reflectance curves are plotted in Fig. 2. Here, sample 1 is a pure gold film, and the value of the gold fill fraction f decreases from approximately 0.85 to 0.4 for samples 2-5.From scanning or transmission electron microscopy (SEM or TEM) studies (see, e.g., the insets of Fig. 1), one sees that the size of the in-plane features of all the nanocomposite films is much smaller than the wavelength. Furthermore, there is very limited structural variation along the thickness dimension. Thus, we here describe the macroscopic optical property of the nanocomposite films in terms of an anisotropic effective dielectric permittivity tensor ជ eff = diag͓ eff,x , eff,y , eff,z ͔. Here, the two in-plane components are equal to each other, eff,x = eff,y , and can be described by using the effective medium approximation (EMA) [12][13][14] aswhere d and m are the dielectric permittivities of the bulk dielectric and metal, respectively, and f is the gold fill fraction. The out-of-plane component, eff,z , is given by eff,z = f...

show abstract

supporting

confidence: 60%

Surface-plasmon polaritons on metal-dielectric nanocomposite films

et al. 2009

View full text Add to dashboard Cite

show abstract

“…21 Under this effective medium approximation, for a porosity of 70%, the d.c. conductivity of ethanol-saturated meso-PS at RT would be about 1.4 · 10 −6 S cm −1 , against a common reported value for bare meso-PS conductivity 22 of about 10 −10 S cm −1 . This means a difference of 4 orders of magnitude between unfilled and saturated meso-PS.…”

Section: A Dielectric Screening In Meso-psmentioning

confidence: 99%

A modified cryostat for photo-electrical characterization of porous materials in controlled atmosphere at very low gas dosage

et al. 2014

View full text Add to dashboard Cite

We developed an integrated system for photo-electrical characterization of materials for sensing applications in strictly controlled environment conditions. The peculiar aspect of this setup is the capability of a fine-tuned gas dosage and a fast dynamic chamber pressure control, coupled with current and voltage sensing within a modified cryostat. To illustrate the capabilities of our system we have characterised both p + -type mesoporous silicon (meso-PS) membranes and nano-crystalline mesoporous titanium dioxide (nc-TiO 2 ) films. In particular, as a main topic is presented a wellresolved characterization of mesoporous silicon electrical conductivity changes induced by presence of ethanol. At low pore filling level adsorbate-shunted conduction is avoided, while dielectric screening effects on frozen doping centres are observable.

show abstract

“…From a Symmetrical Effective Medium Theory 19,20 , the resultant resistivity ρ m of a composite where one of the components has ρ 1 = 0 (superconductor) and fills a fraction p of the space, and the other has resistivity ρ 2 and fills a fraction 1 − p is ρ m = (1/p c )(p c − p)ρ 2 for p < p c and ρ m = 0 for p > p c , where p c is the percolation threshold (which depends on the geometry of the space). In the case of BaPb 1−x Bi x O 3 , ρ 2 would represent the effective resistivity of the material in the normal state, given that the superconducting part associated with ρ 1 can become normal above a certain field or temperature.…”

Section: A Effective Medium Theorymentioning

confidence: 99%

Field-tuned superconductor-insulator transition in BaPb1−xBixO3
Giraldo-Gallo
¹
,
Lee
²
,
Zhang
³

et al. 2012
Phys. Rev. B
23
1
34
0
View full text Add to dashboard Cite

BaPb1−xBixO3 is found to exhibit a field-tuned superconductor to insulator transition for Bi compositions 0.24 ≤ x ≤ 0.29. The magnetoresistance of optimally doped samples manifests a temperature-independent crossing point and scaling of the form ρ(T, H) = ρcF (|H − Hc|T −1/zν ), where Hc is the field determined by the temperature-independent crossing point, and zν = 0.69 ± 0.03. High resolution transmission electron microscopy measurements reveal a complex intergrown nanostructure comprising tetragonal and orthorhombic polymorphs. Data are analyzed in terms of both a classical effective medium theory and a field-tuned quantum phase transition, neither of which provides a completely satisfactory explanation for this remarkable phenomenology.

show abstract

The effective medium approximations: Some recent developments

Cited by 218 publications

References 10 publications

Surface-plasmon polaritons on metal-dielectric nanocomposite films

Surface-plasmon polaritons on metal-dielectric nanocomposite films

A modified cryostat for photo-electrical characterization of porous materials in controlled atmosphere at very low gas dosage

Field-tuned superconductor-insulator transition in BaPb1−xBixO3
Giraldo-Gallo
¹
,
Lee
²
,
Zhang
³

et al. 2012
Phys. Rev. B
23
1
34
0
View full text Add to dashboard Cite

Contact Info

Product

Resources

About

The effective medium approximations: Some recent developments

Cited by 218 publications

References 10 publications

Surface-plasmon polaritons on metal-dielectric nanocomposite films

Surface-plasmon polaritons on metal-dielectric nanocomposite films

A modified cryostat for photo-electrical characterization of porous materials in controlled atmosphere at very low gas dosage

Field-tuned superconductor-insulator transition in BaPb1−xBixO3Giraldo-Gallo1, Lee2, Zhang3 et al. 2012Phys. Rev. B231340View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Field-tuned superconductor-insulator transition in BaPb1−xBixO3
Giraldo-Gallo
¹
,
Lee
²
,
Zhang
³

et al. 2012
Phys. Rev. B
23
1
34
0
View full text Add to dashboard Cite