Magnetic and plasmonic Au/Fe oxide composite NPs: compilation

1) Exchange bias effect in Au-Fe3O4 nanocomposites.
Sayan Chandra, N A Frey Huls, M H Phan, S Srinath, M A Garcia, Youngmin Lee, Chao Wang, Shouheng Sun, Òscar Iglesias and H Srikanth

Nanotechnology 25, 055702 (2014)

Low temperature hysteresis loops simulated after a cooling in a magnetic field h_FC = 100 K as computed by MC simulations of individual nanoparticles with cluster (a) and dimer (b) geometries. The non-magnetic metal is simulated as a hole in the middle for the cluster geometry and a sharp facet for the cluster. Panels (a) and (b) show hysteresis loops of a particle with cluster and dimer geometry, respectively, for two different values of the surface anisotropy constant: k_S = 0.01 (blue squares) equal to the core value k_C = 0.01, and increased surface anisotropy k_S = 30 (red circles). The dashed lines in (b) stand for a spherical particle of the same size as the dimer. The inset displays the contribution of the surface (yellow circles) and core (green squares) spins of a dimer particle to the hysteresis loop for k_s = 30. Snapshots of the spin configurations for cluster ((c) and (d) panels) and dimer ((e) and (f) panels) particles for k_S = 30 obtained at the end of the FC process ((c) and (e) panels) and at the coercive field point of the decreasing field branch ((d) and (f) panels) of the hysteresis loops displayed in figures (a) and (b). For clarity, only a slice of width 4a along the applied field direction and through the central plane of the particles is shown. Surface spins have darker colors and core spins have been colored lighter.

2) Chemically synthesized Au–Fe3O4 nanostructures with controlled optical and magnetic properties. Victor Velasco, Laura Muñoz, Eva Mazarío, Nieves Menéndez, Pilar Herrasti, Antonio Hernando and Patricia Crespo

J. Phys. D: Appl. Phys. 48, 035502 (2015)

(a) ZFC-FC magnetization curves of Fe₃O₄ and Au–Fe₃O₄ NPs measured under an applied field of 25 Oe. (b) Hysteresis loops of Fe₃O₄ and Au–Fe₃O₄ NPs with Au : Fe initial molar ratios of 1 : 1 and 1 : 3 measured at 5 K applying a maximum field of 50.000 Oe. The ferromagnetic behaviour is highlighted in the inset.

3) Spin Dynamics in Hybrid Iron Oxide-Gold Nanostructures.

Tomas Orlando,A. Capozzi, E. Umut, L. Bordonali, M. Mariani, P. Galinetto, F. Pineider, C. Innocenti,  P. Masala,  F. Tabak,  M. Scavini, P. Santini, M. Corti, C . Sangregorio, P. Ghigna, and A. Lascialfari

Journal of Physical Chemistry C 119, 1224 (2015) 

 

We report a broadband ¹H NMR study of the spin dynamics of coated maghemite and gold–maghemite hybrid nanostructures with two different geometries, namely dimers and core–shells. All the samples have a superparamagnetic behavior, displaying a blocking temperature (T_B ∼ 80 K (maghemite), ∼105 K (dimer), ∼150 K (core–shell)), and the magnetization reversal time follows the Vogel–Fulcher law. We observed three different anomalies in ¹H NMR T₁^–1 versus T that decrease in amplitude when increasing the applied magnetic field. We suggest that the anomalies are related to three distinct system dynamics: molecular rotations of the organic groups (240 < T < 270 K), superparamagnetic spin blockage (100 < T < 150 K), and surface–core spin dynamics (T < 25 K). By fitting the T₁^–1 data with a heuristic model, we achieved a good agreement with magnetic relaxation data and literature values for methyl group rotation frequencies.

 

4) Superparamagnetic Au-Fe3O4 nanoparticles: one-pot synthesis, biofunctionalization and toxicity evaluation.

A Pariti, P Desai, S K Y Maddirala, N Ercal, K V Katti, X Liang and M Nath

Materials Research Express 1, 035023 (2014)
5) Spin-Polarization Transfer in Colloidal Magnetic-Plasmonic Au/Iron Oxide Hetero-nanocrystals.
Francesco Pineider, César de Julián Fernández, Valeria Videtta, Elvio Carlino, Awni al Hourani,Fabrice Wilhelm, Andrei Rogalev, P. Davide Cozzoli, Paolo Ghigna, and Claudio Sangregorio

ACS Nano 7, 857 (2013)

We report on the unprecedented direct observation of spin-polarization transfer across colloidal magneto-plasmonic Au@Fe-oxide core@shell nanocrystal heterostructures. A magnetic moment is induced into the Au domain when the magnetic shell contains a reduced Fe-oxide phase in direct contact with the noble metal. An increased hole density in the Au states suggested occurrence of a charge-transfer process concomitant to the magnetization transfer. The angular to spin magnetic moment ratio, m_orb/m_spin, for the Au 5d states, which was found to be equal to 0.38, appeared to be unusually large when compared to previous findings. A mechanism relying on direct hybridization between the Au and Fe states at the core/shell interface is proposed to account for the observed transfer of the magnetic moment.

Plasmonics

Special about Plasmonics in Nanture Photonics
Nature Photonics Volume 6 No 11 pp707-794 (2012)

Quantum plasmons in NPs

Plasmons go quantum

F. Javier García de Abajo
Nature 483, 417 (2012)

a, In particles larger than about 10 nanometres, plasmons emerge as collective oscillations of a gas of conduction electrons, and have a frequency that is uncertain (double-headed arrow) because of collisions among the electrons and between the electrons and the particles' atomic lattice. b, In particles smaller than 10 nm, plasmons are associated with quantum electron transitions between occupied and unoccupied energy levels. As a result, the plasmon frequency and its uncertainty, which Scholl et al. accurately measured, are larger than those for bigger particles.

Quantum plasmon resonances of individual metallic nanoparticles.
Jonathan A. Scholl, Ai Leen Koh & Jennifer A. Dionne
Nature 483, 421 (2012)

Comparison of experimental data with quantum theory. Experimental, EELS-determined localized surface plasmon resonance energies of various Ag particle diameters are overlaid on the absorption spectra generated from the analytic quantum permittivity model (a) and the DFTderived permittivity model (b). The experimental bulk resonance energies are
also included (grey dots) along with the theory prediction (grey line). Classical Mie theory peak prediction is given by the dashed white line. The experimental data begin to deviate significantly from classical predictions for particle diameters smaller than 10nm. Horizontal error bars represent 95% confidence intervals, as calculated through curve fitting and bootstrapping techniques.

Optical activity in Magnetoplasmonic Nanodisks

High Magneto-Optical Activity and Low Optical Losses in Metal-Dielectric Au/Co/Au–SiO2 Magnetoplasmonic Nanodisks.
Juan Carlos Banthí, David Meneses-Rodríguez, Fernando García, María Ujué González, Antonio García-Martín, Alfonso Cebollada, Gaspar Armelles
Advanced Materials 24, OP36 (2012)

a) Sketch of the composition of the fabricated nanodisks. b) AFM image of a selected fabricated structure (15 nm Au/10 nm Co/20 nm SiO₂/15 nm Au).

Plasmon bleaching in Au/FeO dumbbells

Plasmon Bleaching Dynamics in Colloidal Gold−Iron Oxide Nanocrystal Heterodimers.
Alberto Comin, Kseniya Korobchevskaya, Chandramohan George, Alberto Diaspro, and Liberato Manna
Nano Letters 12, 921 (2012)

Transient absorption spectrum, measured at 110 μJ/cm², of gold only and gold/FeO nanocrystals with, overlaid, three black traces corresponding to the positions of the maxima and of the zeros.

Em field distribution in a nanodisk

Probing the Electromagnetic Field Distribution within a Metallic Nanodisk.
David Meneses-Rodríguez , Elías Ferreiro-Vila , Patricia Prieto, José Anguita , María U. González , José M. García-Martín , Alfonso Cebollada, Antonio García-Martín, and Gaspar Armelles
Small 7, 3317 (2011)

Magnetoplasmonics with nano FMs

Designer Magnetoplasmonics with Nickel Nanoferromagnets.
Valentina Bonanni, Stefano Bonetti, Tavakol Pakizeh, Zhaleh Pirzadeh, Jianing Chen, Josep Nogués, Paolo Vavassori, O Rainer Hillenbrand, O Johan Åkerman, and Alexandre Dmitriev
Nano. Lett. 11, 533 (2011)

We introduce a new perspective on magnetoplasmonics in nickel nanoferromagnets by exploiting the phase tunability of the optical polarizability due to localized surface plasmons and simultaneous magneto-optical activity. We demonstrate how the concerted action of nanoplasmonics and magnetization can manipulate the sign of rotation of the reflected light’s polarization (i.e., to produce Kerr rotation reversal) in ferromagnetic nanomaterials and, further, how this effect can be dynamically controlled and employed to devise conceptually new schemes for biochemosensing.

Sailing plasmonic NP

Plasmonic Nanoparticle Chain in a Light Field: A Resonant Optical Sail.
Silvia Albaladejo, Juan José Sáenz, and Manuel I. Marqués
Nano Lett 11, 4597 (2011)

We propose to use a chain made of metallic nanoparticles as a resonant light sail, attached by one end point to a transparent object and propelling it by the use of electromagnetic radiation.

Plasmonic nanoclusters by DNA

DNA-Enabled Self-Assembly of Plasmonic Nanoclusters.
Jonathan A. Fan, Yu He, Kui Bao, Chihhui Wu, Jiming Bao, Nicholas B. Schade, Vinothan N. Manoharan, Gennady Shvets, Peter Nordlander, David R. Liu, and Federico Capasso
Nano Letters 11, 4859 (2011)

DNA-mediated assembly of plasmonic heterotetramers.

Plasmonics

Two publications on the field of plasmons have been issued this week:
1) Special issue on Plasmonics with several Review articles:
Chemical Reviews Vol. 111, Iss. 6 (2011)

 2) Review about surface plasmons in NPs:
Surface plasmons in metallic nanoparticles: fundamentals and applications.
M A Garcia
J. Phys. D 44, 283001 (2011)

Colloidal Plasmonic-Photonic Crystals

Hybrid Colloidal Plasmonic-Photonic Crystals.
Sergei G. Romanov, Alexander V. Korovin , Alois Regensburger , and Ulf Peschel
Adv. Mater. 23, 2515 (2011)

Plasmonic nanostructures

Building plasmonic nanostructures with DNA.
Shawn J. Tan, Michael J. Campolongo, Dan Luo & Wenlong Cheng
Nature Nanotechnology 6, 268 (2011)

Schematic of plasmonic nanostructures assembled from libraries of plasmonic atoms with various DNA motifs.