Ferroplasmons: Intense Localized Surface Plasmons in Metal-Ferromagnetic Nanoparticles

Sachan, Ritesh; Malasi, Abhinav; Ge, Jiwan; Yadavali, Sagar; Krishna, Hare; Gangopadhyay, A. K.; García, Hernando; Duscher, Gerd; Kalyanaraman, R.

doi:10.1021/nn5031719

Cited by 51 publications

(74 citation statements)

References 52 publications

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“…Since the contrast in HAADF image comes from its atomic number (Z) dependence, the bright region in the NSs corresponded to Ag while the darker regions corresponded to Co. The elemental identification was also verified using EELS, as described by us previously for such bimetal systems . In those works performed on glass substrates, we showed that a clear phase segregation of Ag and Co was present in ns‐PLDew NSs, very similar to our observations here for the C substrate.…”

Section: Resultssupporting

confidence: 89%

“…The elemental identifi cation was also verifi ed using EELS, as described by us previously for such bimetal systems. [ 26,27 ] In those works performed on glass substrates, we showed that a clear phase segregation of Ag and Co was present in ns-PLDew NSs, very similar to our observations here for the C substrate. In Figure 4 b, a plan-view HAADF image of bimetallic Au-Co NSs on C is shown.…”

Section: Large-area Coverage Of Nsssupporting

confidence: 89%

“…Representative low‐loss EELS spectra from NSs of the two bimetallic systems presented in Figure are shown in Figure . These bimetals are potential candidates for ultrastable as well as advanced chemical and biological sensing devices . Figure a,b show the low‐loss spectra from one position on the surface of AgCo and AuCo bimetallic NSs, respectively (which were described earlier in Figure ).…”

Section: Resultsmentioning

confidence: 93%

“…These bimetals are potential candidates for ultrastable as well as advanced chemical and biological sensing devices. [ 19,27 ] Figure 7 a,b show the low-loss spectra from one position on the surface of AgCo and AuCo bimetallic NSs, respectively (which were described earlier in Figure 4 ). The region on the surface of the NSs where the spectra were taken, are marked with a square box in the inset images.…”

Section: Plasmonics In Nssmentioning

confidence: 93%

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Laser-Induced Self-Assembled Nanostructures on Electron-Transparent Substrates

Sachan

Malasi

Yadavali

et al. 2014

Part. Part. Syst. Charact.

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Currently, one of the challenges in high‐resolution transmission electron microscopy (TEM) studies of nanomaterials is to make contamination‐free materials in a simple and time‐efficient way. Here, a method is demonstrated that combines nanosecond‐pulsed laser dewetting of thin films with a film float‐off technique to realize nanostructures (NSs) on electron‐transparent substrates in a robust and rapid manner. NSs of metal (Ag) and bimetals (AgCo, AuCo) ranging from 20 to 150 nm are synthesized on thin carbon film deposited on mica substrates. The NS/carbon system is subsequently transferred onto TEM grids by a float‐off process resulting from debonding of the carbon from mica due to their contrasting hydrophobic nature. This process enables the fabrication of different NSs on flexible and electron‐transparent substrates.

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Section: Resultssupporting

confidence: 89%

Section: Large-area Coverage Of Nsssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 93%

Section: Plasmonics In Nssmentioning

confidence: 93%

See 2 more Smart Citations

Laser-Induced Self-Assembled Nanostructures on Electron-Transparent Substrates

Sachan

Malasi

Yadavali

et al. 2014

Part. Part. Syst. Charact.

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“…Bimetallic materials are a promising new way to realize new and/or better plasmonic behaviors [3,4]. In this paper we first use high-resolution transmission electron microscopy to present evidence for ferroplasmons, strong surface plasmons that appear in ferromagnetic metals when in the proximity of noble metal nanostructures.…”

mentioning

confidence: 99%

Ferroplasmons: Novel Plasmons in Metal-Ferromagnetic Bimetallic Nanostructures

Malasi

Passarelli

et al. 2015

Microsc Microanal

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New plasmonic materials are required to enable potential strong coupling of light and magnetism, which could lead to improved data storage and/or completely novel optical materials [1,2]. Bimetallic materials are a promising new way to realize new and/or better plasmonic behaviors [3,4]. In this paper we first use high-resolution transmission electron microscopy to present evidence for ferroplasmons, strong surface plasmons that appear in ferromagnetic metals when in the proximity of noble metal nanostructures. To better understand and explore the origin of these ferroplasmons we have developed a simple approach to synthesize electron transparent nanostructures so as to compare their plasmonic properties by electron energy loss spectroscopy and compare with calculations performed using the discrete dipole approximation (DDA) approach. Fig. 1(a) shows the high angle annular dark field (HAADF) image of a Co-Ag bimetallic nanoparticle formed on an amorphous carbon substrate by pulsed laser dewetting. A Zeiss Libra 200 TEM with a monochromator and energy filter was used to characterize the nanostructure by HAADF mode and electron energy-loss spectroscopy (EELS) at 200 kV. To understand the spatial nature of surface plasmons in these nanoparticles we generated the maps of plasmons from different energy windows, with the 0 to 3 eV data shown in Fig. 1(b-c) and 3 to 5 eV data shown in Fig. 1(d-e). For the 0 -3 eV region, the strongest surface plasmon occurred at 2.6±0.3 eV and measurement of the scattering probability [ Fig. 1(b)] and full width half maxima (FWHM) [ Fig. 1(c)] showed that the Co region had a strong plasmon, called the ferroplasmon. In contrast, analysis of the 3 to 5 eV window showed that a surface plasmon occurred at energy of 3.5 ± 0.3 eV and the scattering probability is shown in Fig. 1(d), while the FWHM is shown in Fig. 1(e). This peak was seen to be highly localized to the Ag region. Similar measurements done on pure Co nanoparticles did not show any evidence for these strong ferroplasmons seen when Co was in the vicinity of Ag.DDA modeling has suggested that ferroplasmons can be a result of electromagnetic coupling between the two metals [2]. To investigate this further, we developed a technique to rapidly prepare electron transparent nanostructures and perform EELS on at different energy windows and compare these experiments with DDA electrodynamics theory. The sample preparation involved a combination of nanosphere lithography and a carbon substrate float-off process. Fig. 1(f) shows the Z-contrast from HAADF imaging of pairs of non-touching bimetallic Co-Ag triangles

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Bimetallic AgCo Nanoparticle Synthesis via Combinatorial Nanosecond Laser‐Induced Dewetting of Thin Films

Paduri,

Harimkar,

Sachan

2024

Adv Eng Mater

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Herein, a combinatorial approach is developed to conduct high‐throughput studies on the nanosecond pulsed laser‐induced dewetting phenomenon of bilayer Ag–Co metallic thin films. Laser irradiation results in the spontaneous rupture of these films in nanosecond timescale, forming bimetallic nanoparticles (NPs) through intermediate stages of hole formation and bicontinuous nanostructures. This approach utilizes bilayer thin films with thickness gradients in both Ag and Co layers (referred to as bigradient samples) while maintaining a constant overall thickness. The laser irradiation on such bigradient bilayer films facilitates control on Ag and Co ratio in the thin films, thus enabling material libraries of Ag–Co NPs covering a large compositional variation. The evolution of NPs with a correlation between NP diameter and interparticle spacings is further studied. The study reveals monotonic increase in NP size and interparticle spacing in Co/Ag bilayer arrangement, while an increase and subsequent decrease in the NP size is observed at 50% Ag in Ag/Co bigradient films. A transition from intermediate stage hole formation to bicontinuous nanostructures with changing composition is also observed. These changes in intermediate stage morphologies and dewetting mechanism are attributed to variation of the free energy of the bilayer system dominated by intermolecular interaction forces.

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Ferroplasmons: Intense Localized Surface Plasmons in Metal-Ferromagnetic Nanoparticles

Cited by 51 publications

References 52 publications

Laser-Induced Self-Assembled Nanostructures on Electron-Transparent Substrates

Laser-Induced Self-Assembled Nanostructures on Electron-Transparent Substrates

Ferroplasmons: Novel Plasmons in Metal-Ferromagnetic Bimetallic Nanostructures

Bimetallic AgCo Nanoparticle Synthesis via Combinatorial Nanosecond Laser‐Induced Dewetting of Thin Films

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