Magnetic interactions between nanoparticles

• Steen Mørup,
• Mikkel Fougt Hansen and
• Cathrine Frandsen

Beilstein J. Nanotechnol. 2010, 1, 182–190, doi:10.3762/bjnano.1.22

• ferromagnetic cobalt covered by a shell of antiferromagnetic CoO [4]: This effect is nowadays utilized in read heads in computer hard disk drives. In a neutron study of Fe3O4/CoO multilayers, van der Zaag et al. [5] found that the Néel temperature of CoO was enhanced due to the exchange interaction with

• ferrimagnetic Fe3O4 layers with a Curie temperature of about 850 K. Similarly, an increase of the Curie temperature of ferrimagnetic γ-Mn2O3 due to interaction with antiferromagnetic MnO has been found in MnO/γ-Mn2O3 core–shell particles [6]. The magnetic properties of non-interacting magnetic nanoparticles are

• , including Fe100−xCx [10], ε-Fe3N [11], γ-Fe2O3 [12][13][14] and Fe3O4 [15] have been investigated. If the particles are randomly distributed and have a random orientation of the easy axes, the magnetic properties can have similarities to those of spin glasses [10][11][14], and therefore these interacting

Magnetic nanoparticles for biomedical NMR-based diagnostics

• Huilin Shao,
• Tae-Jong Yoon,
• Monty Liong,
• Ralph Weissleder and
• Hakho Lee

Beilstein J. Nanotechnol. 2010, 1, 142–154, doi:10.3762/bjnano.1.17

• ][37][38][39][40][41][42]. CLIO nanoparticles contain a superparamagnetic iron oxide core (3–5 nm monocrystalline iron oxide) composed of ferrimagnetic magnetite (Fe3O4) and/or maghemite (γ-Fe2O3). The metallic core is subsequently coated with biocompatible dextran, before being cross-linked with

Magnetic coupling mechanisms in particle/thin film composite systems

• Giovanni A. Badini Confalonieri,
• Philipp Szary,
• Durgamadhab Mishra,
• Maria J. Benitez,
• Mathias Feyen,
• An Hui Lu,
• Leonardo Agudo,
• Gunther Eggeler,
• Oleg Petracic and
• Hartmut Zabel

Beilstein J. Nanotechnol. 2010, 1, 101–107, doi:10.3762/bjnano.1.12

• coupled Fe3O4/CoO [38] and Fe/CoO [39] thin film systems, that the blocking temperature, in this case the temperature at which exchange bias between a FM and an AF thin film disappears, can occur at temperatures below the Néel temperature of CoO (~290 K), in the case of ultra thin films of CoO (less than

Uniform excitations in magnetic nanoparticles

• Steen Mørup,
• Cathrine Frandsen and
• Mikkel Fougt Hansen

Beilstein J. Nanotechnol. 2010, 1, 48–54, doi:10.3762/bjnano.1.6

• Equation 1, and the latter approximation is valid at low temperatures. The linear temperature dependence of the magnetization in nanoparticles was first observed by Mössbauer spectroscopy studies of magnetite (Fe3O4) nanoparticles [3], but it has later been studied in nanoparticles of several other

• the relaxation is fast compared to the timescale of Mössbauer spectroscopy, and the observed magnetic hyperfine field is then given by where B0 is the saturation hyperfine field. Figure 3 shows the temperature dependence of the magnetic hyperfine field of three samples of magnetite (Fe3O4