Optical anisotropy of shaped oriented cobalt nanoparticles by generalized spectroscopic ellipsometry

Gilliot, Mickaël; Naciri, A. En; Johann, L.; Stoquert, J.P.; Grob, J.J.; Müller, D.

doi:10.1103/physrevb.76.045424

Cited by 22 publications

(13 citation statements)

References 76 publications

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“…The optical properties of metal-dielectric composite materials, with cobalt as the corresponding metal, have been recently studied in detail for cobalt spherical and elongated nanoparticles. [41][42][43] In the past, Co-Al 2 O 3 composite were studied for their application as solar selective surface in photothermal energy conversion of solar energy. 44 More recently, the interest has grown because of its potential application of their surface plasmon renonances, 43 45 which in conjunction with the magnetic properties can lead to versatile hybrid magneto-optic and optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Template Assisted Electrochemical Growth of Cobalt Nanowires: Influence of Deposition Conditions on Structural, Optical and Magnetic Properties

Cortés¹,

Lavín²,

Denardin³

et al. 2011

J. Nanosci. Nanotech.

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The influence of electrodeposition potential, pH, composition and temperature of the electrolytic bath on the structure of cobalt nanowires arrays electrodeposited into anodic aluminum oxide (AAO) porous membranes is reported. XRD, SEM, and TEM analysis were employed to characterize structural (crystal phase, crystallographic texture, and grain size), and morphological nanowire properties. It was confirmed that at pH 2 the electrodeposition potential has not influence on the preferred crystallographic orientation of the electrochemically grown Co nanowires. At pH 4 the electrodeposition potential controls the growth of cobalt nanowires along some preferential crystallographic planes. The electrolytic pH bath modulates the fcc or hcp phase exhibited by the cobalt nanowires. Single crystalline nanowires with a hcp phase strongly oriented along the (2021) crystallographic plane were obtained at pH 4 and at -1.1 V (vs. Ag/AgCl), a result not previously reported. High electrolytic bath temperatures contributed to improve the single crystalline character of the cobalt nanowires. The presence of chloride anion in the electrolytic bath also influenced on the structural properties of the resulting cobalt nanowires, improving their crystallinity. The optical reflectance of the samples shows a structure in the UV-blue region that can be assigned to the two-dimensional morphology arising in the shape of the almost parallel nanowires. Magnetic measurements showed that different electrodeposition potentials and electrolytic bath pH lead to different magnetic anisotropies on the nanowire array samples.

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Section: Introductionmentioning

confidence: 99%

Template Assisted Electrochemical Growth of Cobalt Nanowires: Influence of Deposition Conditions on Structural, Optical and Magnetic Properties

Cortés¹,

Lavín²,

Denardin³

et al. 2011

J. Nanosci. Nanotech.

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show abstract

“…In this small-size limit, it is usually claimed that a heterogeneous nanocomposite material can be considered as a homogeneous medium whose macroscopic optical response is described by an effective dielectric tensor. Effective medium theories were developed for a 3D [31][32][33][34][35] or a 2D organization 36,37 of the NPs. In the frequently encountered case of single layers of NPs (2D organization), the simplest method was proposed by Yamaguchi et al three decades ago.…”

Section: Introductionmentioning

confidence: 99%

Advanced optical effective medium modeling for a single layer of polydisperse ellipsoidal nanoparticles embedded in a homogeneous dielectric medium: Surface plasmon resonances

et al. 2012

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We calculate, in the quasistatic coupled dipole approximation, the analytical expressions of the effective dielectric tensor of a single layer of polydisperse ellipsoidal nanoparticles with two of their principal axes in the layer's plane and embedded in a homogeneous dielectric medium. The organization (isotropic or anisotropic) and orientation (without or with a preferential in-plane orientation) of the nanoparticles is taken into account, together with their (possibly correlated) in-plane size, in-plane projected shape, and height distributions. In particular, we propose to describe the response of a layer of nanoparticles presenting a height distribution by using a vertically graded effective medium model. The expressions are tested in the case of finely characterized dielectric/silver/dielectric granular trilayers grown by means of vapor deposition in which the silver coalesced nanoparticles present correlated in-plane size and in-plane projected shape/height distributions and a moderate surface coverage of about 25%. A satisfactory quantitative agreement is obtained between the simulated and measured surface plasmon extinction bands of the metal nanoparticles. This agreement is permitted by the capability of the effective medium model of taking into account the ellipsoidal shape of the nanoparticles. The significant role of the size and shape distributions is also demonstrated.

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“…513,[666][667][668][669][670][671][672][673][674][675][676][677][678] The effect has been repeated in many systems, and as a general rule the results indicate that nanoparticles in a wide range of metals can be elongated with a suitable irradiation condition. Irradiation of 5 nm Ag nanoparticles in silica with 8 MeV Si ions ͑which does not have an energy deposition high enough to be considered a swift heavy ion͒, was based on indirect optical measurements reported to produce particles FIG.…”

Section: B Elongation Of Nanoclusters By Swift Heavy Ionsmentioning

confidence: 99%

Ion and electron irradiation-induced effects in nanostructured materials

Krasheninnikov¹,

Nordlund²

2010

Journal of Applied Physics

922

591

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A common misconception is that the irradiation of solids with energetic electrons and ions has exclusively detrimental effects on the properties of target materials. In addition to the well-known cases of doping of bulk semiconductors and ion beam nitriding of steels, recent experiments show that irradiation can also have beneficial effects on nanostructured systems. Electron or ion beams may serve as tools to synthesize nanoclusters and nanowires, change their morphology in a controllable manner, and tailor their mechanical, electronic, and even magnetic properties. Harnessing irradiation as a tool for modifying material properties at the nanoscale requires having the full microscopic picture of defect production and annealing in nanotargets. In this article, we review recent progress in the understanding of effects of irradiation on various zero-dimensional and one-dimensional nanoscale systems, such as semiconductor and metal nanoclusters and nanowires, nanotubes, and fullerenes. We also consider the two-dimensional nanosystem graphene due to its similarity with carbon nanotubes. We dwell on both theoretical and experimental results and discuss at length not only the physics behind irradiation effects in nanostructures but also the technical applicability of irradiation for the engineering of nanosystems.

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Optical anisotropy of shaped oriented cobalt nanoparticles by generalized spectroscopic ellipsometry

Cited by 22 publications

References 76 publications

Template Assisted Electrochemical Growth of Cobalt Nanowires: Influence of Deposition Conditions on Structural, Optical and Magnetic Properties

Template Assisted Electrochemical Growth of Cobalt Nanowires: Influence of Deposition Conditions on Structural, Optical and Magnetic Properties

Advanced optical effective medium modeling for a single layer of polydisperse ellipsoidal nanoparticles embedded in a homogeneous dielectric medium: Surface plasmon resonances

Ion and electron irradiation-induced effects in nanostructured materials

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