En route to controlled catalytic CVD synthesis of densely packed and vertically aligned nitrogen-doped carbon nanotube arrays

• Slawomir Boncel,
• Sebastian W. Pattinson,
• Valérie Geiser,
• Milo S. P. Shaffer and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2014, 5, 219–233, doi:10.3762/bjnano.5.24

• be used as high surface area electrodes. Apart from this, the ‘bamboo’-like N-CNTs obtained here could provide a new opening in drug delivery systems due to their rigid ‘needle-like’ morphology. These N-CNTs with a high content of ferromagnetic nanoparticles could potentially serve as magnetically

Charge and spin transport in mesoscopic superconductors

• M. J. Wolf,
• F. Hübler,
• S. Kolenda and
• D. Beckmann

Beilstein J. Nanotechnol. 2014, 5, 180–185, doi:10.3762/bjnano.5.18

• obtained by using ferromagnetic and normal-metal detectors, we discriminate charge and spin degrees of freedom. We observe spin injection and long-range transport of pure, chargeless spin currents in the regime of large Zeeman splitting. We elucidate charge and spin transport by comparison to theoretical

• measurement scheme. A central superconducting aluminum wire is contacted by several normal-metal (copper) or ferromagnetic (iron) electrodes attached via thin tunnel barriers. A dc bias voltage Vinj with a small superimposed low-frequency ac excitation is applied to one junction (injector), and the resulting

• different contact distances d, and different material combinations, for which both injector and detector could be either normal (N) or ferromagnetic (F). These configurations will be labeled by AISIB, where A and B denote the injector and detector contacts, respectively. Two examples (NISIN and NISIF) are

Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures

• Rafal Pietruszka,
• Bartlomiej S. Witkowski,
• Grzegorz Luka,
• Lukasz Wachnicki,
• Sylwia Gieraltowska,
• Krzysztof Kopalko,
• Eunika Zielony,
• Piotr Bieganski,
• Ewa Placzek-Popko and
• Marek Godlewski

Beilstein J. Nanotechnol. 2014, 5, 173–179, doi:10.3762/bjnano.5.17

• ][13][14]. ZnO has a 3.37 eV direct band gap at room temperature [15] and a high excitation binding energy of 60 meV. It is intensively studied for light emitters in the near-UV region of the spectrum [16][17], or for spintronic applications [18][19][20], since ferromagnetic thin films of ZnO can be

Spin relaxation in antiferromagnetic Fe–Fe dimers slowed down by anisotropic Dy^III ions

• Valeriu Mereacre,
• Frederik Klöwer,
• Yanhua Lan,
• Rodolphe Clérac,
• Juliusz A. Wolny,
• Volker Schünemann,
• Christopher E. Anson and
• Annie K. Powell

Beilstein J. Nanotechnol. 2013, 4, 807–814, doi:10.3762/bjnano.4.92

• and then increases sharply to reach a maximum of 33.00 cm3·K·mol−1 at 1.8 K, which may be because of an intramolecular ferromagnetic interaction. If the Fe–Fe (Fe(1)–Fe(2) and Fe(3)–Fe(4)) interaction is antiferromagnetic and the Fe–Dy exchange interaction is negligible, then the only ferromagnetic

Nanoglasses: a new kind of noncrystalline materials

• Herbert Gleiter

Beilstein J. Nanotechnol. 2013, 4, 517–533, doi:10.3762/bjnano.4.61

• . More recent examples are light weight metals (e.g., Al), semiconductors (e.g., Si), materials with high strength (e.g., steels), superconductors, ferroelectrics, special ferromagnetic materials etc. The main reason for the preference of crystalline materials is the fact that one can control their

• spectrum of the ribbon or of the isolated Fe90Sc10 nanometer-sized clusters and (2) a ferromagnetic component (six-line subspectrum: red curve in Figure 12). As the ferromagnetism at ambient temperature is observed only if the Fe90Sc10 nanospheres are compacted (Figure 12), one is led to conclude that it

• paramagnetic at this temperature, in agreement with the results reported in the literature [41][42]. In contrast, the magnetization curve of the Fe90Sc10 nanoglass indicates that it is ferromagnetic and it exhibits an average magnetization of about 1.05 μB per Fe atom. According to the Mössbauer spectrum of

Ferromagnetic behaviour of Fe-doped ZnO nanograined films

• Boris B. Straumal,
• Svetlana G. Protasova,
• Andrei A. Mazilkin,
• Thomas Tietze,
• Eberhard Goering,
• Gisela Schütz,
• Petr B. Straumal and
• Brigitte Baretzky

Beilstein J. Nanotechnol. 2013, 4, 361–369, doi:10.3762/bjnano.4.42

• contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area sGB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough

• investigated. The films were deposited by using the wet chemistry “liquid ceramics” method. The samples demonstrate ferromagnetic behaviour with Js up to 0.10 emu/g (0.025 μB/f.u.ZnO) and coercivity Hc ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe

• content can be explained by the changes in the structure and contiguity of a ferromagnetic “grain boundary foam” responsible for the magnetic properties of pure and doped ZnO. Keywords: Fe; ferromagnetism; grain boundaries; ZnO; Introduction The possibility of ferromagnetism (FM) in oxides has been

Antiferromagnetic coupling of TbPc₂ molecules to ultrathin Ni and Co films

• David Klar,
• Svetlana Klyatskaya,
• Andrea Candini,
• Bernhard Krumme,
• Kurt Kummer,
• Philippe Ohresser,
• Valdis Corradini,
• Valentina de Renzi,
• Roberto Biagi,
• Loic Joly,
• Jean-Paul Kappler,
• Umberto del Pennino,
• Marco Affronte,
• Heiko Wende and
• Mario Ruben

Beilstein J. Nanotechnol. 2013, 4, 320–324, doi:10.3762/bjnano.4.36

• . On both substrates the TbPc2 molecules couple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface. Keywords: magnetic anisotropy; magnetic coupling; single molecule magnets; X-ray

• with regards to the applicability of magnetic molecules for industrial usage is the control of the magnetic properties. Mn- and Fe-porphyrin molecules were successfully coupled to ferromagnetic thin films, leading to the alignment of the magnetic moments of the metal ions parallel to the film [15][16

• ][17] or antiparallel due to an interlayer of oxygen [18][19]. Recently, it was shown that TbPc2 molecules can be magnetically coupled to a ferromagnetic Ni substrate [20]. The magnetic anisotropy and field dependence were also studied for TbPc2 in a submonolayer on Cu(100) [21] and on

Hydrogen-plasma-induced magnetocrystalline anisotropy ordering in self-assembled magnetic nanoparticle monolayers

• Alexander Weddemann,
• Judith Meyer,
• Anna Regtmeier,
• Irina Janzen,
• Dieter Akemeier and
• Andreas Hütten

Beilstein J. Nanotechnol. 2013, 4, 164–172, doi:10.3762/bjnano.4.16

• σII = 1.14 nm. According to Hütten et al. [3], the smaller species are superparamagnetic while the larger contain a certain degree of ferromagnetic components. Sample preparation Both samples were prepared in a procedure introduced by Puntes et al. [14] under airless conditions. For the synthesis of

• homogeneously magnetized along their volume. Therefore, each individual particle may be approached by its magnetic moment , with MS being the saturation magnetization of the material, VP the particle volume and the angular components. The equilibrium state of a system of ferromagnetic components is a solution

Sub-10 nm colloidal lithography for circuit-integrated spin-photo-electronic devices

• Adrian Iovan,
• Marco Fischer,
• Roberto Lo Conte and
• Vladislav Korenivski

Beilstein J. Nanotechnol. 2012, 3, 884–892, doi:10.3762/bjnano.3.98

• ][24][25], and consisted of a spin-majority/minority ferromagnetic bi-layer Fe0.7Cr0.3(10 nm)/Fe(15 nm) [25] capped with Cu(10 nm), for spin-population-inversion injection. Even though the deposition technique is not highly directional, we find that the angle of incidence through the 10 nm openings in

• behaviour and showed that the fabricated nanocontact arrays are of high quality. We next demonstrate a point-contact array with the contacts having a magnetic core. More specifically, the core material is a majority/minority ferromagnetic bi-layer of Fe/Fe0.7Cr0.3 [28], where due to the opposite spin

• exchange splitting in the ferromagnetic point contact core (10–100 mV, see [24][25] for more details). Such high-bias, high-density, spin-polarized injection produces large nonequilibrium spin accumulation in the contact core, which allows spin-flip photon-emission transitions, vertical in the momentum of

Highly ordered ultralong magnetic nanowires wrapped in stacked graphene layers

• Abdel-Aziz El Mel,
• Jean-Luc Duvail,
• Eric Gautron,
• Wei Xu,
• Chang-Hwan Choi,
• Benoit Angleraud,
• Agnès Granier and
• Pierre-Yves Tessier

Beilstein J. Nanotechnol. 2012, 3, 846–851, doi:10.3762/bjnano.3.95

• the quality of the nickel nanowires after annealing attributed to a decrease of the roughness of the nickel surface and to a reduction of the defect density. This new type of graphene–ferromagnetic-metal nanowire appears to be an interesting building block for spintronic applications. Keywords

• : carbon; ferromagnetic; graphene; nanofabrication; nanowires; nickel; phase separation; Introduction Magnetic nanowires have been widely investigated during the last two decades for fundamental physics [1][2][3][4][5][6][7], and nano-engineering [7][8][9][10]. The various properties of these

• template methods [1][2][3][4][5][6][7][8][9][10][11][12], ferromagnetic nanowires still suffer from their relatively short length, which cannot reach up to the macroscopic scale. In addition, the manipulation of such one-dimensional (1D) nanostructures is often considered as a complicated process and a

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

• Ulf Wiedwald,
• Felix Haering,
• Stefan Nau,
• Carsten Schulze,
• Herbert Schletter,
• Denys Makarov,
• Alfred Plettl,
• Karsten Kuepper,
• Manfred Albrecht,
• Johannes Boneberg and
• Paul Ziemann

Beilstein J. Nanotechnol. 2012, 3, 831–842, doi:10.3762/bjnano.3.93

• ferromagnetic at room temperature down to a Co concentration of about 15 atom % [34]. MOKE remanence curves were measured by saturating the sample, subsequently applying a reverse field and recording the remanent magnetization (Figure 9). The angle θ of the external magnetic field with respect to the sample

Focused electron beam induced deposition: A perspective

• Michael Huth,
• Fabrizio Porrati,
• Christian Schwalb,
• Marcel Winhold,
• Roland Sachser,
• Maja Dukic,
• Jonathan Adams and
• Georg Fantner

Beilstein J. Nanotechnol. 2012, 3, 597–619, doi:10.3762/bjnano.3.70

• to the next section. Co–Pt FEBID structures As a second example of a binary FEBID experiment recent results on the Co–Pt system are reviewed [33]. The binary phase diagram of Co–Pt features several ferromagnetic intermetallic compounds. The most prominent of these is the L10 phase of CoPt, which has

• electron irradiated sample shows an increase by about two orders of magnitude. The conductivity levels off below 50 K and shows only a small residue of the conductance drop at 12 K. The Hall data indicate now a ferromagnetic state at room temperature with increasing coercive field as the sample is cooled

• to low temperatures. This indicates that the phase transformation from an amorphous to the ordered L10 phase is accompanied by a corresponding phase transition from a superparamagnetic to a moderately hard ferromagnetic state. The overall magnetic properties of these samples depend strongly on the

Strong spin-filtering and spin-valve effects in a molecular V–C₆₀–V contact

• Mohammad Koleini and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2012, 3, 589–596, doi:10.3762/bjnano.3.69

• ]. The C60 molecule is considered as an attractive anchoring group for molecular electronics due to its mechanical robustness [8]. Moreover, the lowest unoccupied molecular orbital (LUMO) of C60 is close to the Fermi level of ferromagnetic elements which makes spin injection relatively easy [9], and

• , ferromagnetic (FM) and anti-ferromagnetic (AFM) spin alignment between atoms of tip and adatom, have been considered. The site on the C60 with the highest binding energy for a V adatom is η5, which is roughly over the center of a pentagon of a C60, and due to the symmetric structure of the C60, this site is

P-wave Cooper pair splitting

• Henning Soller and
• Andreas Komnik

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

• effects. The result is the Hamiltonian where represents the resonant level. Throughout the rest of this exposition we use units in which e = = kB = 1 and restrict ourselves to a quantum dot on resonance Δd = 0. Ferromagnetic electrodes are described in the language of electron field operators Ψk,α,σ

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

• Maximilian Schneiderbauer Daniel Wastl Franz J. Giessibl Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany 10.3762/bjnano.3.18 Abstract Magnetic force microscopy (MFM) allows one to image the domain structure of ferromagnetic samples by probing the

• . Regions of aligned spins, called domains, are used, for example, to store bits of information on hard discs. Such ferromagnetic domains have much larger magnetic dipole moments, as many atoms contribute to the resulting moment. To probe magnetic structures on the atomic as well as on the domain-size scale

• between a tip atom with fixed spin orientation and a sample atom is measured (Figure 1c). Imaging magnetic domains by Magnetic Force Microscopy (MFM) [6][7] is nowadays well-established. MFM images the magnetic-dipole interaction of a ferromagnetic tip and a domain-structured sample (Figure 1a). Typically

Analysis of fluid flow around a beating artificial cilium

• Mojca Vilfan,
• Gašper Kokot,
• Andrej Vilfan,
• Natan Osterman,
• Blaž Kavčič,
• Igor Poberaj and
• Dušan Babič

Beilstein J. Nanotechnol. 2012, 3, 163–171, doi:10.3762/bjnano.3.16

• diameter 55 nm [24]) in water. To prevent aggregation of the beads, we coated them with BSA (bovine serum albumin), 10 mg/mL, for 4 h in an ultrasonic bath. One end of the assembled chain was attached to the surface through prefabricated ferromagnetic-nickel anchoring sites. The nickel dots were

Enhancement of the critical current density in FeO-coated MgB₂ thin films at high magnetic fields

• Andrei E. Surdu,
• Hussein H. Hamdeh,
• Imad A. Al-Omari,
• David J. Sellmyer,
• Alexei V. Socrovisciuc,
• Andrei A. Prepelita,
• Ezgi T. Koparan,
• Ekrem Yanmaz,
• Valery V. Ryazanov,
• Horst Hahn and
• Anatolie S. Sidorenko

Beilstein J. Nanotechnol. 2011, 2, 809–813, doi:10.3762/bjnano.2.89

• that ferromagnets strongly suppress superconductivity, and even a small ferromagnetic region can be a strong pin, as was confirmed in experiments with NbTi wires containing nanometer-sized arrays of Ni pins [9]. We placed the ferromagnetic nanoparticles on the surface, instead of in the volume of the

Interaction of spin and vibrations in transport through single-molecule magnets

• Falk May,
• Maarten R. Wegewijs and
• Walter Hofstetter

Beilstein J. Nanotechnol. 2011, 2, 693–698, doi:10.3762/bjnano.2.75

• an isotropic Heisenberg spin-exchange with the conduction band electron spin where τ is the vector of Pauli matrices. The coupling J is assumed to be anti-ferromagnetic, which, as pointed out in [16], depends on the spins of the virtual charge states of the SMM [17][18]. One might expect that

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

• , Spain 10.3762/bjnano.2.59 Abstract The most outstanding feature of scanning force microscopy (SFM) is its capability to detect various different short and long range interactions. In particular, magnetic force microscopy (MFM) is used to characterize the domain configuration in ferromagnetic materials

• such as thin films grown by physical techniques or ferromagnetic nanostructures. It is a usual procedure to separate the topography and the magnetic signal by scanning at a lift distance of 25–50 nm such that the long range tip–sample interactions dominate. Nowadays, MFM is becoming a valuable

• every kind of force to the total force measured leads to serious problems for obtaining quantitative information from the measurements [4]. Among those SFM techniques, magnetic force microscopy (MFM) [5] was developed to characterize the domain configuration of ferromagnetic thin films, rather than the

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• support easily overwhelms the total magnetic moment of the tiny amount of ferromagnetic material in the NPs. In the present system one can benefit from the paramagnetic response of the Pt(111) film and paramagnetic impurities in MgO compensating the diamagnetic signal of the substrate. Since the

• diamagnetism of MgO is temperature independent and the paramagnetic signal follows Curie’s law at low temperatures [40], compensation can be achieved at an appropriate temperature, which is experimentally determined to be around 29 K for our samples. As the non-ferromagnetic background was strongly reduced, a

Effect of large mechanical stress on the magnetic properties of embedded Fe nanoparticles

• Srinivasa Saranu,
• Sören Selve,
• Ute Kaiser,
• Luyang Han,
• Ulf Wiedwald,
• Paul Ziemann and
• Ulrich Herr

Beilstein J. Nanotechnol. 2011, 2, 268–275, doi:10.3762/bjnano.2.31

• with a straight line and has been subtracted from the data. Note that the total ferromagnetic moment of Fe nanoparticles (8.3·10−6 emu) in saturation is only about 2% of the paramagnetic signal of the Ta substrate at 5000 Oe. At this temperature, the particles show a ferromagnetic behaviour. It should

• observed at 300 K compared to 10 K, there is a small remnant magnetization indicating that at least some of the particles show ferromagnetic behaviour at 300 K. This may be attributed to the presence of a small fraction of larger Fe nanoparticles (as indicated by the size distribution given in Figure 1

Extended X-ray absorption fine structure of bimetallic nanoparticles

• Carolin Antoniak

Beilstein J. Nanotechnol. 2011, 2, 237–251, doi:10.3762/bjnano.2.28

• larger lattice parameters, but all the changes are rather small. Similar trends are reported for other ferromagnetic or antiferromagnetic materials, e.g. for bcc and fcc Fe [95]. Experimentally, the magnetic moments of FePt nanoparticles were found to be reduced with respect to the correspondent bulk

Structural and magnetic properties of ternary Fe_1–xMn_xPt nanoalloys from first principles

• Markus E. Gruner and
• Peter Entel

Beilstein J. Nanotechnol. 2011, 2, 162–172, doi:10.3762/bjnano.2.20

• functional devices. Conclusion: Addition of Mn effectively increases the stability of single crystalline L10 particles over multiply twinned morphologies. This, however, compromises the stability of the ferromagnetic phase due to an increased number of antiferromagnetic interactions. The consequence is that

• effective interlayer coupling and mediates an indirect ferromagnetic (FM) interaction between the adjacent 3d layers, which overrides the smaller direct antiferromagnetic coupling across the Pt layer. The validity of this model has been verified in large scale first principles calculation of a partially

• below for FePt). The ferromagnetic, ordered icosahedron, which is nearly degenerate for Fe265Pt296, has become unstable in the Mn–Pt system for sizes above 147 atoms. During the geometric optimization procedure it transforms downhill to a perfect L10 cuboctahedron. This proves that the Mackay path is a

Structure, morphology, and magnetic properties of Fe nanoparticles deposited onto single-crystalline surfaces

• Armin Kleibert,
• Wolfgang Rosellen,
• Mathias Getzlaff and
• Joachim Bansmann

Beilstein J. Nanotechnol. 2011, 2, 47–56, doi:10.3762/bjnano.2.6

• process might be accompanied by a complex reshaping of the particles. Keywords: epitaxy; iron; magnetic nanoparticles; Ni(111); RHEED; spontaneous self-alignment; STM; W(110); XMCD; Introduction Ferromagnetic clusters and nanoparticles have gained huge interest due to their interesting fundamental

• properties as well as their possible applications in data storage media, chemistry, biotechnology and medicine [1][2][3][4]. First, Stern–Gerlach measurements proved that ferromagnetic particles may exhibit enhanced and strongly size-dependent magnetic moments [5]; and even non-magnetic materials can show

• Experiments on exposed mass-filtered Fe nanoparticles on (ferromagnetic) supports require in situ cluster deposition as well as surface sensitive analysis techniques performed under ultrahigh vacuum conditions. To motivate the need of our combined approach, we first introduce the arc cluster ion source (ACIS

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

• 10.3762/bjnano.1.22 Abstract We present a short overview of the influence of inter-particle interactions on the properties of magnetic nanoparticles. Strong magnetic dipole interactions between ferromagnetic or ferrimagnetic particles, that would be superparamagnetic if isolated, can result in a

• magnetic dipole interactions can have a strong influence on, e.g., the magnetic dynamics in samples containing ferromagnetic or ferrimagnetic nanoparticles. If nanoparticles or thin films are in close proximity, exchange interactions between surface atoms can be significant. An important example of

• magnetic proximity effects is exchange bias, which manifests itself as a shift of the hysteresis curves obtained after field cooling of a ferromagnetic or ferrimagnetic material in contact with an antiferromagnetic material [1][2][3]. This was first observed in nanoparticles consisting of a core of