UHV deposition and characterization of a mononuclear iron(III) β-diketonate complex on Au(111)

• Irene Cimatti,
• Silviya Ninova,
• Valeria Lanzilotto,
• Luigi Malavolti,
• Luca Rigamonti,
• Brunetto Cortigiani,
• Matteo Mannini,
• Elena Magnano,
• Federica Bondino,
• Federico Totti,
• Andrea Cornia and
• Roberta Sessoli

Beilstein J. Nanotechnol. 2014, 5, 2139–2148, doi:10.3762/bjnano.5.223

• ) [1][2][3][4][5][6]. SMMs are molecules whose magnetic moment reorients orders of magnitude slower than in normal paramagnets and results in a memory effect at low temperature. Such a behaviour is often accompanied by spectacular quantum features, for example, resonant quantum tunnelling of the

• molecules in the adopted experimental conditions. The amplitude of the XMCD% signal reaches approximately 80% of the isotropic contribution (σ− + σ+)/2, as expected for a set of independent HS Fe3+ ions with their magnetic moment fully aligned in the direction of the externally applied magnetic field [37

Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt

• Peter Robaschik,
• Pablo F. Siles,
• Daniel Bülz,
• Peter Richter,
• Manuel Monecke,
• Michael Fronk,
• Svetlana Klyatskaya,
• Daniel Grimm,
• Oliver G. Schmidt,
• Mario Ruben,
• Dietrich R. T. Zahn and
• Georgeta Salvan

Beilstein J. Nanotechnol. 2014, 5, 2070–2078, doi:10.3762/bjnano.5.215

• TbPc2/Co heterojunction was already proposed to serve as a model system for a SMM semiconducting layer on top of a ferromagnetic electrode for a future spintronic device. The chemical and magnetic properties of this interface were investigated by Klar et al. and it was found that the magnetic moment of

Quasi-1D physics in metal-organic frameworks: MIL-47(V) from first principles

• Danny E. P. Vanpoucke,
• Jan W. Jaeken,
• Stijn De Baerdemacker,
• Kurt Lejaeghere and
• Veronique Van Speybroeck

Beilstein J. Nanotechnol. 2014, 5, 1738–1748, doi:10.3762/bjnano.5.184

• account: the intra-chain coupling Jc, and the inter-chain coupling Ji (cf. Figure 1a). The V magnetic moment in the current systems can be obtained by projection of the electron density onto atomic orbitals. However, in such an approach the magnitude of the obtained moment will strongly depend on the

Designing magnetic superlattices that are composed of single domain nanomagnets

• Derek M. Forrester,
• Feodor V. Kusmartsev and
• Endre Kovács

Beilstein J. Nanotechnol. 2014, 5, 956–963, doi:10.3762/bjnano.5.109

• large magnetic moment, then these particles will primarily have only dipolar interaction. However, when the distance between these particles decreases, the inter-particle interaction will be modified. The latter depends on the specific media separating the particles. If this is a metal then there

Magnetic anisotropy of graphene quantum dots decorated with a ruthenium adatom

• Igor Beljakov,
• Velimir Meded,
• Franz Symalla,
• Karin Fink,
• Sam Shallcross and
• Wolfgang Wenzel

Beilstein J. Nanotechnol. 2013, 4, 441–445, doi:10.3762/bjnano.4.51

• type high-symmetry edge (armchair or zigzag), allowing the clear separation of the physics of these two common edge types. We find that for all flakes and adatom positions investigated, the Ru magnetic moment prefers to lie in the plane of the island, and that the difference in energy between the most

• red arrows indicating the direction of the minimum-energy in-plane position. Correlation between the magnetic moment and the in-plane versus out-of-plane anisotropy, EIO, see Equation 1, for armchair-graphene quantum dots (AGQDs) and zigzag-graphene quantum dots (ZGQDs) consisting of 36 and 90 carbon

In situ monitoring magnetism and resistance of nanophase platinum upon electrochemical oxidation

• Eva-Maria Steyskal,
• Stefan Topolovec,
• Stephan Landgraf,
• Heinz Krenn and
• Roland Würschum

Beilstein J. Nanotechnol. 2013, 4, 394–399, doi:10.3762/bjnano.4.46

• gained by means of a direct comparison of the charge-induced response of two different properties, namely electrical resistance and magnetic moment. For this purpose, four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the

• regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the

• amount of deposited oxygen, is considered to be primarily caused by charge-carrier scattering processes at the metal–electrolyte interfaces. In comparison, the decrease of the magnetic moment upon positive charging appears to be governed by the electric field at the nanocrystallite–electrolyte interfaces

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

• contribution from the substrate and the sample holder. The inset shows the magnified central part of the magnetisation curve. Dependence of the saturation magnetization Js (magnetic moment in units of Bohr magnetons per ZnO formula units) on the Fe concentration in ZnO nanograined polycrystals obtained by the

• indicates the experimental data obtained by the authors’ own investigations (for symbols and references see the text). Dependence of the saturation magnetization (magnetic moment per iron atom in units of Bohr magnetons) on the Fe concentration in ZnO obtained by other methods such as magnetron sputtering

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

• moment of Tb could be forced in the plane. However, because of the large magnetic anisotropy barrier of the TbPc2 molecules of 73 meV [20][31], we expect the magnetic moment of the Tb ions not to be forced to the in-plane direction by the Co magnetization since the coupling energies presented in [20] are

• antiferromagnetic contribution is very small compared to the dominating paramagnetic signal, because the Co magnetization direction is not in the direction of the molecular easy axis. If a very large coupling strength between the molecules and the Co substrate exceeds the magnetic anisotropy barrier, the magnetic

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

• magnetic properties [3][4] or specific biological surface coatings [5][6] have been established. Such nanocrystals have a nonzero magnetization at zero field because of finite-size effects. Nevertheless, due to their superparamagnetic nature, the effective magnetic moment of an ensemble of noninteracting

• FePt alloyed particles, meet this requirement [12][13]. The magnetic-moment vector aligns with the easy axis due to energy minimization. In the transition from a single free particle to a closed monolayer, stray-field contributions of contiguous particles need to be taken into account. For such

• components are aligned parallel to the magnetization directions of the magnetic equilibrium state of the system itself. If particles with low magnetocrystalline anisotropy are considered, the magnetic equilibrium state is mainly dominated by dipolar coupling. In this case, the magnetic-moment vectors do not

Plasmonic oligomers in cylindrical vector light beams

• Mario Hentschel,
• Jens Dorfmüller,
• Harald Giessen,
• Sebastian Jäger,
• Andreas M. Kern,
• Kai Braun,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2013, 4, 57–65, doi:10.3762/bjnano.4.6

• as cylindrical vector beams, is a simple task. Plasmonic oligomers Originally, we intended to utilize split-ring resonators (SRR) as magnetic atoms. These U-shaped nanostructures support a plasmonic mode which is associated with a strong magnetic moment. Arranging SRRs in a chain and thus coupling

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

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

• used a 41 GB hard disc from MAXTOR with a bit density of approximately 2 Gbit/in2, resulting in a bit size of approximately (200 × 600) nm2. Assuming a rigid tip magnetization in the z-direction, the magnetostatic force is a function of the magnetic moment of the tip and the gradient of the magnetic

• the same sample one can therefore vary the interaction strength by means of the magnetic moment of the tip and the lift-mode height. In a first attempt we used an electrochemically etched bulk-iron tip (see inset in Figure 2a) and magnetized it for scanning by means of a strong permanent magnet. With

• silicon MFM cantilever setup (Nanosurf Flex AFM). Moreover we measured the expected bit density of ≈1.9 Gbit/in2 in Figure 2b. As large magnetic moments of the probing tip can influence and even destroy the magnetic structure of the observed sample, a small magnetic moment is desirable. However, tips with

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

• . We investigate the course of the saturation magnetization Ms as well as of the initial susceptibility χini with time. While Ms gives information on the residual content of magnetic material in the sample, χini is a measure of the average magnetic moment involved in the remagnetization process for the

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

• the magnetic moment of the sample covered with FeO nanoparticles are considerably higher than the respective values of the uncovered sample; as is especially clear to see in the field range 0–4 T at 4.2 K. The curves in Figure 3 to Figure 6 show the values of the critical current density Jc as a

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

• microscopy (KPFM) and MFM. The KPFM technique allows us to compensate in real time the electrostatic forces between the tip and the sample by minimizing the electrostatic contribution to the frequency shift signal. This is a great challenge in samples with low magnetic moment. In this work we studied an

• based materials [10][11]. In general, these materials present low magnetic moment at room temperature. In addition, since the substrate and the nanomagnets present quite different electronic behavior, the sample can exhibit large surface potential differences, which cause heterogeneous electrostatic

• tip and the sample as magnetic dipoles and, hence, the magnetic force is proportional to the magnetic moment of both the tip and sample (mtip and msam) [22] and decays with the distance as z4 [30]. Typical values of the three components of the force for three tip–sample distances are displayed in

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

• ) films with micron-sized grains, local alloying at the film surface was established. Signatures of alloy formation were evident from magnetic investigations. Upon annealing to temperatures up to 380 °C, we found an increase both of the coercive field and of the Co orbital magnetic moment, indicating the

• ) generated in the Pt film. In addition, because the background is curved, a quantitative determination of the (spin and orbital) magnetic moments from the XMCD sum rules is problematic. We will therefore resort to the more robust procedure of evaluating the ratio of the orbital magnetic moment to the

• effective spin magnetic moment µL/µSeff, where the effective spin moment µSeff = µS + 7 µT contains two contributions: The spin moment µS, as well as the magnetic dipole moment µT, which relates to the anisotropy of the spin density distribution. As the magnetic dipole term may be quite significant in CoPt

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

• magnetization of the particle can be represented by one single magnetic moment which adjusts its direction under the influence of local anisotropies, such as the magneto-crystalline anisotropy field, and external fields. In addition, thermal fluctuations may lead to instability of the magnetization over time

Extended X-ray absorption fine structure of bimetallic nanoparticles

• Carolin Antoniak

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

• moment at the Fe sites. Changes of the orbital magnetic moment and the Pt moments are negligible with respect to the strong decrease of the Fe spin magnetic moment. The results from SPR-KKR calculations are shown in Figure 8. For the lattice constants, the experimentally determined values were used [68

• ] as input for the calculations. It can clearly be seen that the spin magnetic moments at the Pt sites remained largely unchanged around μS(Pt) ≈ 0.22 μB for different compositions between x = 32 atom % and x = 68 atom %, the orbital magnetic moment increased slightly with increasing Fe content from μl

• (Pt) ≈ 0.042 μB to 0.048 μB. The orbital magnetic moment at the Fe sites showed a similar behaviour and increased from μl(Fe) ≈ 0.06 μB to 0.078 μB in the composition range investigated in this work. The Fe spin magnetic moment decreased with increasing Fe content from about 3.0 μB at x = 32 atom % to

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

• bias effects originating from uncompensated surface spins has been observed experimentally in annealed binary MnPt nanoparticles with diameters between 2.3 nm and 4.1 nm [76]. The kink of the otherwise linear evolution of the spin magnetic moment of the icosahedral cluster at large Mn content is due to

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

• of the individual anisotropy axis as sketched in Figure 2g. Thus, in the present XMCD experiments we would only probe the averaged projection of the magnetization in the particle ensemble which leads to an apparently reduced magnetic moment in the sum rule analysis. The fact that we observed bulk

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

• nanoparticles can have a significant influence on the magnetic properties. In a sample of randomly distributed nanoparticles with average magnetic moment μ and average separation d, the dipole interaction energy of a particle is on the order of [9] where μ0 is the permeability of free space. In samples with

• antiferromagnetic material the net magnetization vanishes because the sublattice magnetizations have identical size but opposite directions. However, in nanoparticles, the finite number of magnetic ions results in a small net magnetic moment because of uncompensated spins in the surface and/or in the interior of

• the particles [34]. This magnetic moment is, however, usually so small that dipole interactions are almost negligible and the influence of dipole interactions on the superparamagnetic relaxation is therefore also expected to be negligible [35]. Nevertheless, several Mössbauer studies of, for example

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

• particular direction defined by magnetic anisotropy. At sufficiently high temperatures (above blocking temperature), thermal energy can induce free rotation of the magnetic moment. Thus, when MNPs are grouped together, they display a form of paramagnetic behavior, known as superparamagnetism: MNPs assume

• , targeted MNPs can be used to tag cell surface markers to impart a magnetic moment (Figure 1b). The change of 1/T2 is proportional to the number of MNPs bound, and also indicative of the abundance of relevant surface biomarkers. Unlike MRSw assays, this magnetic tagging strategy requires washing steps to

• magnetization is known to increase with particle size [33]. Ideally, each magnetic spin within a bulk magnetic material would be aligned parallel to the external magnetic field. However, in the nanoscale regime, surface spins tend to be tilted, a feature that reduces the overall magnetic moment. By increasing

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

• to that of β-Mn, characterized by a short-range order. The average magnetic moment per Fe atom is raised to 2.59 µB (for comparison, bulk value of metallic Fe: 2.2 µB). Even if the spontaneous magnetization decreases rapidly as compared to bulk materials, it remains enhanced even up to room

• analysis of the low temperature Mössbauer spectra, show a broad distribution of large hyperfine fields. The largest hyperfine fields display the largest isomer shifts. This indicates a progressive increase of the magnetic moment inside the particle from the core to the outer shell. The components

• past ten years have allowed the development of precise studies on the influence of size reduction on the magnetic properties of nanoparticles (NPs) down to the nanometer scale. A first spectacular result was the observation of the enhancement of the atomic magnetic moment in NPs of classical 3d

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

• and the Co layer can be obtained from measurements of the magnetic moment vs temperature (Figure 5) after zero-field cooling (ZFC) and field cooling (FC). Generally, the system is first cooled down from relatively high temperatures (here 380 K) in a zero field, then a magnetic field is applied and the

• is the decrease of the magnetic moment in the FC curve for decreasing temperatures below Tb. This trend has already been recognized as indicating a collective particle behavior, a so-called super-spin glass (SSG) state [21][24][27][36][37]. The peak temperature then marks the 'blocking temperature

• section NPs/thin-film system showing the CoO layer at the interface with NPs. (b) The corresponding diffraction pattern where the following phases are identified: 1) CoO (200), 2) Fe2O3 (311), 3) Si (111), 4) Fe2O3 (111). ZFC/FC magnetic moment vs temperature measured in 500 Oe for a NP monolayer (green

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

• chemical, physical and medical fields [1]. A common example is their employment in microfluidic devices: Due to their permanent magnetic moment, they can be controlled via external, inhomogeneous magnetic fields [2] and also be detected by magnetoresistive sensors [3] which allows for the magneto-based

• important area in the field of nanoparticles based on their interesting properties which provide various advantages in comparison to monometallic nanocrystals. An example can be found with CoFe particles which have a strongly increased magnetic moment per atom in comparison to pure Co particles [29

• longer stable magnetization configurations but the magnetic moment permanently switches between different orientations. For uniaxial crystal anisotropy, the superparamagnetic size limit needs to meet where kB is the Boltzmann constant, T the absolute temperature, Kuni the first anisotropy constant and