Magnetic−Plasmonic Core−Shell Nanoparticles

Abstract

Nanoparticles composed of magnetic cores with continuous Au shell layers simultaneously possess both magnetic and plasmonic properties. Faceted and tetracubic nanocrystals consisting of wüstite with magnetite-rich corners and edges retain magnetic properties when coated with an Au shell layer, with the composite nanostructures showing ferrimagnetic behavior. The plasmonic properties are profoundly influenced by the high dielectric constant of the mixed-iron-oxide nanocrystalline core. A comprehensive theoretical analysis that examines the geometric plasmon tunability over a range of core permittivities enables us to identify the dielectric properties of the mixed-oxide magnetic core directly from the plasmonic behavior of the core-shell nanoparticle.

Colloidal Magnetic Heterostructured Nanocrystals with Asymmetric Topologies: Seeded-Growth Synthetic Routes and Formation Mechanisms

“…In addition, while a metal or semiconductor domain can enable optical detection (e.g., via excitonic or LSPR absorption, or photoluminescence), a magnetic module can be utilized for complementary purposes, such as for magnetic resonance imaging (MRI), optical imaging, and magnetic separation (Choi et al, , 2008Jun et al, 2007;Jiang et al, 2008;Xu et al, 2008;Gao et al, 2009;Schladt et al, 2010;Bigall et al, 2012;Lim and Majetich, 2013). The existence of bonding heterointerfaces through which dissimilar materials can electronically communicate has clearly been recognized to impact on the magnetic (Xu et al, 2008;Lee et al, 2010a;Umut et al, 2012;Pineider et al, 2013;Kim and Song, 2014;Schick et al, 2014;López-Ortega et al, 2015;Velasco et al, 2015), optical (Levin et al, 2009;Korobchevskaya et al, 2011;Comin et al, 2012), transport (Lee et al, 2010a), magneto-optical Armelles et al, 2013), (electro)catalytic (Yin et al, 2008;Wang et al, 2009aWu et al, 2009;Lee et al, 2010b;George et al, 2011aGeorge et al, , 2013Jang et al, 2011b;Lin and Doong, 2011;Chen et al, 2012;Sun et al, 2012), and energy-storing properties of appropriately engineered MHNCs . Examples of MHNCs derived from heterogeneous deposition pathways are collected in Figures 2B-Q.…”

Magnetic and noble metal nanocomposites for separation and optical detection of biological species

“…Bi-functional silanes such as aminopropyltriethoxysilane (APTES), which form a monolayer (or at least a thin layer) with an outer amino group ensuring water dispersibility are typically used. In one notable case 86 the exchange of the surface layer of oleic acid/octylyamine present after the thermal reaction was reported. The Au layer was again grown in two steps, with initial attachment of 2 nm Au NPs.…”

Boosting Fano resonances in single layered concentric core–shell particles

“…1.d. For such particle the cavity mode is located at lower energy than the sphere mode and the subradiant anti-bonding and super-radiant bonding modes shift re-spectively to lower and higher energies as the core-to-shell ratio increases 47,48 . Again, in the weak hybridization regime a FR can be clearly observed, as shown in Fig.…”

“…2.a and 2.b. In the experimental works that have addressed the study of particles with large dielectric constant cores 47,48 , the shell thickness was thin enough to lead to strong hybridization and avoid excitation of strong FR. These FR in the total scattering spectra have been also overlooked in theoretical studies on the optical properties of large dielectric constant core and metallic-shells that have focused either on the strong hybridization regime 60 or on off-resonance field enhancement and FR in directional scattering spectra 61 .…”