Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology

• Maria Eugenia Toimil-Molares

Beilstein J. Nanotechnol. 2012, 3, 860–883, doi:10.3762/bjnano.3.97

• nanowires were successfully grown from nickel [57], cobalt [79], and iron [80]. The growth of Fe-based nanowires with controllable size, aspect ratio, and magnetic anisotropy in FeCl3 and FeCl2 solutions was investigated by Song et al. They employed FeCl3 and FeCl2 solutions, studied the nanowire growth

Spontaneous dissociation of Co₂(CO)₈ and autocatalytic growth of Co on SiO₂: A combined experimental and theoretical investigation

• Kaliappan Muthukumar,
• Harald O. Jeschke,
• Roser Valentí,
• Evgeniya Begun,
• Johannes Schwenk,
• Fabrizio Porrati and
• Michael Huth

Beilstein J. Nanotechnol. 2012, 3, 546–555, doi:10.3762/bjnano.3.63

• , namely by air plasma cleaning or a focused electron beam pre-irradiation. We observe a spontaneous dissociation of the precursor molecules as well as autodeposition of cobalt on the pretreated SiO2 surfaces. We also find that the differences in metal content and relative stability of these deposits

• in FEBID to obtain granular deposits with differing compositions of cobalt [11]. Electronic and physical properties, such as grain size and metal content of these deposits, depend strongly on the deposition and pretreatment conditions of the substrate. By regulating these conditions, deposits of

• conditions, and we aim to relate the observations to the plasma and electron irradiation conditions prevailing in FEBID experiments. Experimental Cobalt growth and imaging experiments were carried out at room temperature in a dual-beam scanning electron microscope (FEI Nova NanoLab 600) with a Schottky

Imaging ultra thin layers with helium ion microscopy: Utilizing the channeling contrast mechanism

• Gregor Hlawacek,
• Vasilisa Veligura,
• Stefan Lorbek,
• Tijs F. Mocking,
• Antony George,
• Raoul van Gastel,
• Harold J. W. Zandvliet and
• Bene Poelsema

Beilstein J. Nanotechnol. 2012, 3, 507–512, doi:10.3762/bjnano.3.58

• the formation of cobalt nanoclusters, an atomically clean Ge{001} substrate was obtained by prolonged 800 eV Ar+ ion sputtering followed by annealing of the sample through resistive heating at 1100 K. Several monolayers of Co were evaporated by resistively heating a tungsten wire wrapped with a pure

• larger deviation from the initial particle trajectory. We will discuss this in more depth in the next paragraph. For the present case in which a light adlayer (either carbon or cobalt) covers a heavier substrate (silicon or germanium), (1) does not play a significant role and (2) will be weak in general

P-wave Cooper pair splitting

• Henning Soller and
• Andreas Komnik

Beilstein J. Nanotechnol. 2012, 3, 493–500, doi:10.3762/bjnano.3.56

• [66]. Another experiment realized a superconductor–ferromagnet–superconductor junction based on Al and Co electrodes with two closely spaced cobalt wires bridging two aluminum electrodes [76]. In this experiment the resistance in the case of antiparallel and parallel magnetization of the two wires was

qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

• Maximilian Schneiderbauer,
• Daniel Wastl and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 174–178, doi:10.3762/bjnano.3.18

• acquisition times. To benchmark our setup, we reduced the magnetic moment of the tip by attaching a commercial MFM cantilever tip (NanoWorld Pointprobe MFMR, coated with approx. 40 nm cobalt alloy) onto a qPlus sensor. This has been done before in tuning-fork setups in room-temperature ultrahigh-vacuum

• parameters f0 = 24097 Hz, k = 1250 Nm−1, Q = 1161, A = 20 nm and lift height 45 nm. (a) Topography and (b) lift-mode frequency shift. Lift Mode FM-MFM image employing a qPlus sensor with a commercial cobalt-coated MFM cantilever tip attached to it (see inset in a). Flattened raw data with imaging parameters

Improvement of the oxidation stability of cobalt nanoparticles

• Celin Dobbrow and
• Annette M. Schmidt

Beilstein J. Nanotechnol. 2012, 3, 75–81, doi:10.3762/bjnano.3.9

• Celin Dobbrow Annette M. Schmidt Department für Chemie, Universität zu Köln, Luxemburger Str. 116, D-50939 Köln, Germany 10.3762/bjnano.3.9 Abstract In order to enhance the resistance of cobalt nanoparticles to oxidation in air, the impact of different stabilization strategies on the isothermal

• decrease of the magnetization for all particle charges, indicating that the process is dominated by a diffusion of oxygen to the cobalt core and a radial growth of the oxide layer from the particle surface to the core. A significant deceleration of the oxidation process was observed for all alcohol

• -passivated particle preparations, and this resulted finally in a stagnation effect. The stabilizing effect increases in the sequence Co@OA/MeOH < Co@OA/EtOH < Co@OA/iPrOH. For polymer-coated particle preparations Co@PCL and Co@PS, the deceleration was even more pronounced. The results demonstrate that cobalt

Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

• Miriam Jaafar,
• Oscar Iglesias-Freire,
• Luis Serrano-Ramón,
• Manuel Ricardo Ibarra,
• Jose Maria de Teresa and
• Agustina Asenjo

Beilstein J. Nanotechnol. 2011, 2, 552–560, doi:10.3762/bjnano.2.59

• Discussion In the present work we have studied cobalt nanowires grown by focused-electron-beam-induced deposition (FEBID). The sample growth was performed in a commercial dual beam® equipment using a field emission scanning electron microscope with Co2(CO)8 as gas precursor. The substrate material used in

• μm, the width of the wires varies between 125 nm and 2 μm, and the thickness between 50 nm and 200 nm. An appropriate selection of the growth parameters leads to high-purity deposits (over 95% Co) with magnetic properties similar to those of bulk cobalt [35] and good domain wall conduit behavior [36

• -plane coercive field higher than the magnetic field values to be applied in the experiments. In addition, micromagnetic simulations have been performed by means of the object oriented micromagnetic framework (OOMMF) code [41] and with the polycrystalline cobalt values [37] and a cell size of 5 nm. As

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

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

• applications. Doped-ferrite nanoparticles The magnetization of ferrite nanoparticles can be further enhanced by doping the ferrite with ferromagnetic elements such as manganese (Mn), cobalt (Co) or nickel (Ni) [23][27][45]. Among the singly-doped ferrite MNPs, MnFe2O4 nanoparticles were found to exhibit the

Ultrafine metallic Fe nanoparticles: synthesis, structure and magnetism

• Olivier Margeat,
• Marc Respaud,
• Catherine Amiens,
• Pierre Lecante and
• Bruno Chaudret

Beilstein J. Nanotechnol. 2010, 1, 108–118, doi:10.3762/bjnano.1.13

• organometallic approach [17]. We have, for example, shown that cobalt NPs prepared by the decomposition of an organometallic precursor under mild conditions in the presence of a stabilising polymer exhibit physical properties similar to those of free cobalt clusters [18]. In this article, we report the chemical

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

• thin cobalt film of 20 nm thickness was grown on top of the NPs by ion-beam sputtering from a Co target at 3.9 × 10−4 mbar with a base pressure of 1 × 10−8 mbar. To prevent oxidation of the Co surface, the sample was finally capped with a 3 nm thick layer of Cu. A reference composite sample was

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

• Alexander Weddemann,
• Inga Ennen,
• Anna Regtmeier,
• Camelia Albon,
• Annalena Wolff,
• Katrin Eckstädt,
• Nadine Mill,
• Michael K.-H. Peter,
• Jochen Mattay,
• Carolin Plattner,
• Norbert Sewald and
• Andreas Hütten

Beilstein J. Nanotechnol. 2010, 1, 75–93, doi:10.3762/bjnano.1.10

• the C-terminal region of Mms6. In this study, cobalt ferrite nanoparticles not known to occur in magnetotactic bacteria were synthesized. Cobalt and iron salts were added to the c25-mms6 mixture and incubated at 4 °C. The mixture was stirred under argon flux until it reached room temperature and then

• diagrams of the bulk materials. In order to illustrate the growth dynamics and material distribution along the particle volume, we consider two miscible compounds, A1 and A2, such as iron and cobalt carbonyl. The result should fall into the classes 1 to 3. Precursors decay at different decay rates ki which

• magnetization MS, and is given by where µ0 is the vacuum permeability. In this work, we focus on particles of sizes between 5 to 20 nm; the single domain limits of cobalt and iron nanocrystals are on this size scale. The crystalline microstructure introduces energetically favorable easy axes and directions of

Flash laser annealing for controlling size and shape of magnetic alloy nanoparticles

• Damien Alloyeau,
• Christian Ricolleau,
• Cyril Langlois,
• Yann Le Bouar and
• Annick Loiseau

Beilstein J. Nanotechnol. 2010, 1, 55–59, doi:10.3762/bjnano.1.7

• thickness of 10 nm was deposited. On the top of the amorphous carbon, a 3 nm layer of a-Al2O3 was deposited. Then, cobalt and platinum were alternatively deposited using pure Co and Pt targets irradiated with an energy density of 4.4 J/cm2 in order to obtain Co50Pt50 NPs. The crystalline structure of as

Enhanced visible light photocatalysis through fast crystallization of zinc oxide nanorods

• Sunandan Baruah,
• Mohammad Abbas Mahmood,
• Myo Tay Zar Myint,
• Tanujjal Bora and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2010, 1, 14–20, doi:10.3762/bjnano.1.3

• recombination rate is lower than the rate of electron transfer to adsorbed molecules. There are reports on the enhancement of visible light absorption in ZnO by doping with, e.g., cobalt (Co) [18], manganese (Mn) [19], lead (Pb) and silver (Ag) [16], etc. Photocatalytic activity comparable to doped ZnO was also