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Unusual magneto-optical behavior induced by local dielectric variations under localized surface plasmon excitations.

González-Díaz JB, García-Martín A, Reig GA - Nanoscale Res Lett (2011)

Bottom Line: We study the effect of global and local dielectric variations on the polarization conversion rps response of ordered nickel nanowires embedded in an alumina matrix.When considering local changes, we observe a non-monotonous behavior of the rps, its intensity unusually modified far beyond to what it is expected for a monotonous change of the whole refractive index of the embedding medium.This is related to the local redistribution of the electromagnetic field when a localized surface plasmon is excited.

View Article: PubMed Central - HTML - PubMed

Affiliation: IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, Tres Cantos, E-28760 Madrid, Spain. juanb@imm.cnm.csic.es.

ABSTRACT
We study the effect of global and local dielectric variations on the polarization conversion rps response of ordered nickel nanowires embedded in an alumina matrix. When considering local changes, we observe a non-monotonous behavior of the rps, its intensity unusually modified far beyond to what it is expected for a monotonous change of the whole refractive index of the embedding medium. This is related to the local redistribution of the electromagnetic field when a localized surface plasmon is excited. This finding may be employed to develop and improve new biosensing magnetoplasmonic devices.

No MeSH data available.


Related in: MedlinePlus

(Top) EM field distribution of a system composed of Ni nanowires. Embedded in an n = 1.4 dielectric medium and surrounded by an n = 1.7 shell for different thicknesses, at the energies where the LSP is excited (maximum field concentration within the nanowire). (Bottom) Same as in top but for a system composed of Ni nanowires embedded in an n = 1.7 dielectric medium and surrounded by an n = 1.4 shell. In both cases, the inner and outer dashed rings delimit the nanowire and shell sections, respectively. (Graph) Average EM field intensity within the Ni nanowires as a function of the shell thickness. The continuous and dotted lines correspond to different uniform background mediums (n = 1.7 and n = 1.4 refractive indexes, respectively), whereas circles (dots) correspond to the system described at top (bottom).
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Figure 4: (Top) EM field distribution of a system composed of Ni nanowires. Embedded in an n = 1.4 dielectric medium and surrounded by an n = 1.7 shell for different thicknesses, at the energies where the LSP is excited (maximum field concentration within the nanowire). (Bottom) Same as in top but for a system composed of Ni nanowires embedded in an n = 1.7 dielectric medium and surrounded by an n = 1.4 shell. In both cases, the inner and outer dashed rings delimit the nanowire and shell sections, respectively. (Graph) Average EM field intensity within the Ni nanowires as a function of the shell thickness. The continuous and dotted lines correspond to different uniform background mediums (n = 1.7 and n = 1.4 refractive indexes, respectively), whereas circles (dots) correspond to the system described at top (bottom).

Mentions: Similar to the previous analysis on global dielectric changes, these results might be a consequence of the EM field distribution within the nanowires. On top (bottom) of Figure 4, such distribution corresponding to the n = 1.7 (n = 1.4) shell is depicted at the energies where the LSP is excited. As it can be observed, when the shell presents a smaller refractive index (bottom) than the embedding matrix, the EM field within the nanowires decreases. Moreover, as the shell thickness increases, the EM field reaches a minimum that matches with that observed in the /rps/ calculations. This can be better seen in the graph of Figure 4, where we present the intensity of the average EM field within the nanowires for the (a) dielectric environments (dots). On the other hand, when the shell has a larger refractive index than the embedding matrix (b), the EM field increases within the nanowires. The average EM field for this system (circles) shows (see Figure 4) a maximum that again coincides with that obtained for the polarization conversion. This lead us to conclude that the origin of the enhanced or reduced /rps/ response in the shelled nanowires system can be ascribed to the redistribution of the EM field at the metal/dielectric interface induced by the LSP excitation, i.e., any variation of the refractive index in the vicinity of the wires affects the EM field, thus inducing a larger perturbation of the MO response.


Unusual magneto-optical behavior induced by local dielectric variations under localized surface plasmon excitations.

González-Díaz JB, García-Martín A, Reig GA - Nanoscale Res Lett (2011)

(Top) EM field distribution of a system composed of Ni nanowires. Embedded in an n = 1.4 dielectric medium and surrounded by an n = 1.7 shell for different thicknesses, at the energies where the LSP is excited (maximum field concentration within the nanowire). (Bottom) Same as in top but for a system composed of Ni nanowires embedded in an n = 1.7 dielectric medium and surrounded by an n = 1.4 shell. In both cases, the inner and outer dashed rings delimit the nanowire and shell sections, respectively. (Graph) Average EM field intensity within the Ni nanowires as a function of the shell thickness. The continuous and dotted lines correspond to different uniform background mediums (n = 1.7 and n = 1.4 refractive indexes, respectively), whereas circles (dots) correspond to the system described at top (bottom).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211503&req=5

Figure 4: (Top) EM field distribution of a system composed of Ni nanowires. Embedded in an n = 1.4 dielectric medium and surrounded by an n = 1.7 shell for different thicknesses, at the energies where the LSP is excited (maximum field concentration within the nanowire). (Bottom) Same as in top but for a system composed of Ni nanowires embedded in an n = 1.7 dielectric medium and surrounded by an n = 1.4 shell. In both cases, the inner and outer dashed rings delimit the nanowire and shell sections, respectively. (Graph) Average EM field intensity within the Ni nanowires as a function of the shell thickness. The continuous and dotted lines correspond to different uniform background mediums (n = 1.7 and n = 1.4 refractive indexes, respectively), whereas circles (dots) correspond to the system described at top (bottom).
Mentions: Similar to the previous analysis on global dielectric changes, these results might be a consequence of the EM field distribution within the nanowires. On top (bottom) of Figure 4, such distribution corresponding to the n = 1.7 (n = 1.4) shell is depicted at the energies where the LSP is excited. As it can be observed, when the shell presents a smaller refractive index (bottom) than the embedding matrix, the EM field within the nanowires decreases. Moreover, as the shell thickness increases, the EM field reaches a minimum that matches with that observed in the /rps/ calculations. This can be better seen in the graph of Figure 4, where we present the intensity of the average EM field within the nanowires for the (a) dielectric environments (dots). On the other hand, when the shell has a larger refractive index than the embedding matrix (b), the EM field increases within the nanowires. The average EM field for this system (circles) shows (see Figure 4) a maximum that again coincides with that obtained for the polarization conversion. This lead us to conclude that the origin of the enhanced or reduced /rps/ response in the shelled nanowires system can be ascribed to the redistribution of the EM field at the metal/dielectric interface induced by the LSP excitation, i.e., any variation of the refractive index in the vicinity of the wires affects the EM field, thus inducing a larger perturbation of the MO response.

Bottom Line: We study the effect of global and local dielectric variations on the polarization conversion rps response of ordered nickel nanowires embedded in an alumina matrix.When considering local changes, we observe a non-monotonous behavior of the rps, its intensity unusually modified far beyond to what it is expected for a monotonous change of the whole refractive index of the embedding medium.This is related to the local redistribution of the electromagnetic field when a localized surface plasmon is excited.

View Article: PubMed Central - HTML - PubMed

Affiliation: IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, Tres Cantos, E-28760 Madrid, Spain. juanb@imm.cnm.csic.es.

ABSTRACT
We study the effect of global and local dielectric variations on the polarization conversion rps response of ordered nickel nanowires embedded in an alumina matrix. When considering local changes, we observe a non-monotonous behavior of the rps, its intensity unusually modified far beyond to what it is expected for a monotonous change of the whole refractive index of the embedding medium. This is related to the local redistribution of the electromagnetic field when a localized surface plasmon is excited. This finding may be employed to develop and improve new biosensing magnetoplasmonic devices.

No MeSH data available.


Related in: MedlinePlus