Magnetic properties of iron cluster/chromium matrix nanocomposites

• Arne Fischer,
• Robert Kruk,
• Di Wang and
• Horst Hahn

Beilstein J. Nanotechnol. 2015, 6, 1158–1163, doi:10.3762/bjnano.6.117

• antiferromagnetic (AFM) phases a spin exchange coupling occurs and a part of the magnetic moments of the FM phase become pinned. This results in an increased magnetic anisotropy manifesting itself as an exchange bias effect (EB) [3]. The EB appears as a horizontal shift of the magnetization loops, the EB field Heb

• influence of inter-cluster interactions the dependency on the cluster size should be first considered for the larger cluster distances. As a starting point for the analysis one could refer to the simplest model of non-interacting particles with an uniaxial anisotropy in a non-magnetic matrix. Here one would

• expect a simple proportionality , where Keff is an effective anisotropy constant and V the particle volume. Indeed, the measured TB show some rudimentary size dependence, especially at large DNN, but they do not scale linearly with the cluster size. Also the estimated Keff of (0.8–1.3) × 106 J/m3 is

Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

• Oleksandr V. Dobrovolskiy,
• Maksym Kompaniiets,
• Roland Sachser,
• Fabrizio Porrati,
• Christian Gspan,
• Harald Plank and
• Michael Huth

Beilstein J. Nanotechnol. 2015, 6, 1082–1090, doi:10.3762/bjnano.6.109

• the formation of the CoPt L10 phase with strongly increased magnetic anisotropy compared to pure Co. Here, we employ direct writing of Pt and Co layers by FEBID and demonstrate by means of in situ post-processing how to locally tune the coercive field and the remanent magnetization of layered Co/Pt

• the sample plane and, hence, the out-of-plane magnetization was probed by the measurements. This means that first the shape anisotropy of the stripe had to be overcome and all recorded loops relate to the hard-axis magnetization behavior. The reference Co-based sample A shows no hysteresis, whereby U

• carbon. Thus, in the course of the reaction, carbon is partially removed from the deposit causing a reduction of the deposit thickness. The magnetic behavior of the thin polycrystalline Co stripe A is dominated not by the magnetocrystalline anisotropy, but rather by the shape anisotropy causing the

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

• Lisa Michez,
• Kai Chen,
• Fabien Cheynis,
• Frédéric Leroy,
• Alain Ranguis,
• Haik Jamgotchian,
• Margrit Hanbücken and
• Laurence Masson

Beilstein J. Nanotechnol. 2015, 6, 777–784, doi:10.3762/bjnano.6.80

• -dimensional (2D) and one-dimensional (1D) Co nanostructures has shown that magnetic properties are highly size dependent, due to the low coordination of the atoms of atomic-scale nanostructures [1][18]. For such nanostructures, enhanced magnetic anisotropy energy (MAE) and orbital moment have been evidenced

• as compared to the bulk material. Concerning 1D nanostructures, additional effects, especially with regards to magnetic anisotropy, are expected, related to their anisotropic shape [1][19][20]. Since metallic substrates are known to strongly influence the magnetic properties of the supported

• structure is therefore used to study the magnetic anisotropy in the Co nanolines. The hysteresis loops, obtained from the XMCD signal, were recorded at 4 K for different angles Θ varying from normal incidence (Θ = 0°) to grazing incidence (Θ = 70°) using the measurement geometry presented in Figure 4b. Note

Manipulation of magnetic vortex parameters in disk-on-disk nanostructures with various geometry

• Maxim E. Stebliy,
• Alexander G. Kolesnikov,
• Alexey V. Ognev,
• Alexander S. Samardak and
• Ludmila A. Chebotkevich

Beilstein J. Nanotechnol. 2015, 6, 697–703, doi:10.3762/bjnano.6.70

• by using OOMMF software [9] with standard parameters for Py: Ms = 860 Gs, exchange stiffness A = 1.38 · 106 erg/cm, damping factor α = 0.05 [11]. The magnetic anisotropy was chosen zero in order not to insert an asymmetry of magnetic properties into the system. Dimension of the simulated disk-on-disk

Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation

• Guoke Wei,
• Jinliang Wang and
• Yu Chen

Beilstein J. Nanotechnol. 2015, 6, 686–696, doi:10.3762/bjnano.6.69

• extinction that reach the maxima at polarization angles of 90 and 270° and the minima at 0 and 180°. Interestingly, the absorption follows the same polarization dependence as the EFavg, while the scattering and extinction exhibit a different behavior. Previously, Zhao et al. observed that the anisotropy of

In situ observation of biotite (001) surface dissolution at pH 1 and 9.5 by advanced optical microscopy

• Chiara Cappelli,
• Daniel Lamarca-Irisarri,
• Jordi Camas,
• F. Javier Huertas and
• Alexander E. S. Van Driessche

Beilstein J. Nanotechnol. 2015, 6, 665–673, doi:10.3762/bjnano.6.67

• the existence of a surface energy distribution. In agreement with the above consideration the variability of biotite reactivity is an intrinsic factor of its crystalline anisotropy, i.e., surface energy variance, and thermodynamic parameters, such as activation energy, are not representative of the

Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Xabier Quintana and
• José M. Otón

Beilstein J. Nanotechnol. 2015, 6, 396–403, doi:10.3762/bjnano.6.39

• scale: CNTs are several orders of magnitude longer than LC molecules, while their width is only 2–3 times as much. In a typical configuration, an MWCNT-doped LC with positive electric anisotropy is oriented homogeneously (i.e., parallel to the outer plates). Applying a saturation voltage between the

• ]: lower frequencies lead to flickering from LC reorientation following the electric field, while higher frequencies may affect the dielectric anisotropy [13]. Within this restricted frequency range, LC cells may be considered to have a simplified EEC consisting of a resistor in series with the parallel

• above mentioned operating frequency range, from 100 Hz to 10 kHz. As Cr is proportional to the dielectric permittivity, its value is expected to vary with the applied voltage upon reorientation of the material, due to the dielectric anisotropy of LC. For MWCNT-doped LC cells, one could also expect a

Nanoparticle shapes by using Wulff constructions and first-principles calculations

• Georgios D. Barmparis,
• Zbigniew Lodziana,
• Nuria Lopez and
• Ioannis N. Remediakis

Beilstein J. Nanotechnol. 2015, 6, 361–368, doi:10.3762/bjnano.6.35

• and in this way anisotropy can be easily induced [60]. A typical model for a metal surface in equilibrium with surfactants is shown in Figure 3. Complex materials Complex materials such as those proposed in hydrogen storage also benefit from nanoparticle properties that are linked to improved atomic

Multifunctional layered magnetic composites

• Maria Siglreitmeier,
• Baohu Wu,
• Tina Kollmann,
• Martin Neubauer,
• Gergely Nagy,
• Dietmar Schwahn,
• Vitaliy Pipich,
• Damien Faivre,
• Dirk Zahn,
• Andreas Fery and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2015, 6, 134–148, doi:10.3762/bjnano.6.13

• characteristic for superparamagnetic material [39] with a particle size less than 20 nm. Due to magnetic anisotropy the hysteresis curve at T = 2 K shows ferrimagnetic hysteresis. The saturation magnetization for all analyzed samples is around 26 emu/g at 298 K and 36 emu/g at 2 K which are similar values

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• orthogonal functionalization of the surfaces [30][40][41]. In addition to the extrinsic characteristics arising from exploiting the anisotropy, efficient charge separation [42], magnetic interaction [43], or spin-polarization transfer [44] at the interface of the hetero-nanoparticle can be realized by

• active component toward metal-organic reactions. For instance, this enhanced catalytic activity in comparison to the single component nanoparticles was demonstrated for Ni@Fe2O3 [45] or Pt@Fe3O4 [46]. Furthermore, the magnetic anisotropy and coercivity of Fe3O4 was significantly increased due to

• the protein corona of silica nanoparticles. Moreover, no size-dependent particle-protein binding effect was observed while studying nanoparticles with a diameter of 125 nm, 20 nm, and 8 nm [114]. Introducing the anisotropy of Janus particles as another variable to the formation/analysis of the protein

Nanobioarchitectures based on chlorophyll photopigment, artificial lipid bilayers and carbon nanotubes

• Marcela Elisabeta Barbinta-Patrascu,
• Stefan Marian Iordache,
• Ana Maria Iordache,
• Nicoleta Badea and
• Camelia Ungureanu

Beilstein J. Nanotechnol. 2014, 5, 2316–2325, doi:10.3762/bjnano.5.240

• 0.3 nm/s scan rate. Fluorescence analysis The fluorescence emission spectra of Chla in liposomes and hybrid structures were collected on a Perkin-Elmer, LS55 fluorescence spectrometer. The samples were excited with 430 nm excitation light. Fluorescence anisotropy measurements were carried out on the

• emission window, respectively. The anisotropy was calculated as the mean value of seven independent measurements, at a specified temperature, using the equation: where I represents the relative fluorescence intensity, the subscripts v and h represent the vertical and horizontal orientation of the

• obtained by excitation at λ = 430 nm and the emission fluorescence maximum of Chla incorporated in biomimetic membranes and in biohybrids was at 680 nm. The fluorescence anisotropy of biohybrids is greater than that of liposomes (Figure 4), thus Chla sensed a more rigid environment. This makes Chla

Influence of the supramolecular architecture on the magnetic properties of a Dy^III single-molecule magnet: an ab initio investigation

• Julie Jung,
• Olivier Cador,
• Kevin Bernot,
• Fabrice Pointillart,
• Javier Luzon and
• Boris Le Guennic

Beilstein J. Nanotechnol. 2014, 5, 2267–2274, doi:10.3762/bjnano.5.236

• hydrogen bonds play an important role in the modulation of the electrostatic environment around the DyIII center that governs the nature of its magnetic ground-state and the orientation of its anisotropy axes. We thus show here that SMM properties that rely on supramolecular organization may not be

• moment of the molecule and its magnetic anisotropy [1]. Most of SMMs have been characterized as bulk crystalline material in which intermolecular magnetic interactions are expected to be negligible when compared to the intramolecular ones. The magnetic properties of a compound have then a molecular

• extensively characterize the magnetic anisotropy of the molecules [9][10][35][36][37][38] and its evolution with ligand modifications [39][40][41]. These studies have been performed mainly on lanthanide-based SMMs as these ions are expected to be extremely sensitive to modifications of the surrounding [42][43

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

• 58 nm TbPc2 film on Co. TbPc2 films exhibit a uniaxial anisotropy of the dielectric function similar to many planar phthalocyanines, for example, CuPc [13] or H2Pc [14]. Consequently, the dielectric function parallel (in-plane) and perpendicular (out-of-plane) to the sample surface differs . For a

• the dielectric tensor using Equation 1: where i = x, y, z. From the anisotropy of the extinction coefficient k in the Q band region (1.6–2.0 eV), it is possible to estimate the molecular orientation [13][14]. According to the model described in [16] we assume that two electronic transition dipole

• spectral range of 0.7–5.0 eV with an energy step width of 0.02 eV. Three different angles of incidence (50°, 60° and 70°) were exploited for increased sensitivity of the optical anisotropy of the films. The initially linear polarized light becomes elliptically polarized light after reflection on the sample

Cathode lens spectromicroscopy: methodology and applications

• T. O. Menteş,
• G. Zamborlini,
• A. Sala and
• A. Locatelli

Beilstein J. Nanotechnol. 2014, 5, 1873–1886, doi:10.3762/bjnano.5.198

• shown that the addition of oxygen modifies the pattern anisotropy while preserving the periodic structure [69]. Moreover, the Pd–O bispecies layer is stable upon lowering the temperature from above 1000 K down to room temperature. The different adlayer patterns that can be obtained by varying the amount

• of oxygen on the surface are depicted in Figure 10a. The changes in the pattern anisotropy are driven by the magnitude and sign of stress variations on the surface, which are both dependent on the presence and amount of oxygen [69]. The stability of the Pd–O stripes on W(110) at lower temperatures

• map in Figure 10b (right panel). This is a surprising confirmation of the magnetocrystalline anisotropy strength dominating the shape anisotropy. Iron oxides find wide application in several fields of research, among others magnetism and heterogeneous catalysis. In both cases, the heteroepitaxial

Equilibrium states and stability of pre-tensioned adhesive tapes

• Carmine Putignano,
• Luciano Afferrante,
• Luigi Mangialardi and
• Giuseppe Carbone

Beilstein J. Nanotechnol. 2014, 5, 1725–1731, doi:10.3762/bjnano.5.182

• theoretical investigations about rough contact mechanics [25][26][27][28][29], the role of roughness in this kind of systems is not yet well understood. Furthermore, viscoelasticity, which entails prominent effects in terms of friction and contact anisotropy [30][31], has not yet been included in analytical

Probing the electronic transport on the reconstructed Au/Ge(001) surface

• Franciszek Krok,
• Mark R. Kaspers,
• Alexander M. Bernhart,
• Marek Nikiel,
• Benedykt R. Jany,
• Paulina Indyka,
• Mateusz Wojtaszek,
• Rolf Möller and
• Christian A. Bobisch

Beilstein J. Nanotechnol. 2014, 5, 1463–1471, doi:10.3762/bjnano.5.159

• two contacts leading to a current flow across the surface. Thus, if the main contribution of the total current is flowing through the Au reconstructed 1D domains, the impact of the predicted conductance anisotropy should be observed as a variation of the electrochemical potential in the vicinity of

Restructuring of an Ir(210) electrode surface by potential cycling

• Khaled A. Soliman,
• Dieter M. Kolb,
• Ludwig A. Kibler and
• Timo Jacob

Beilstein J. Nanotechnol. 2014, 5, 1349–1356, doi:10.3762/bjnano.5.148

• in- and outside a UHV chamber. It was found that the presence of oxygen is crucial for the faceting process on Ir(210) [21][22]. Theoretical calculations for the Ir(210) system, based on first principles, provided supportive information. It was shown that, due to the anisotropy in surface free energy

Self-organization of mesoscopic silver wires by electrochemical deposition

• Sheng Zhong,
• Thomas Koch,
• Stefan Walheim,
• Harald Rösner,
• Eberhard Nold,
• Aaron Kobler,
• Torsten Scherer,
• Di Wang,
• Christian Kübel,
• Mu Wang,
• Horst Hahn and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2014, 5, 1285–1290, doi:10.3762/bjnano.5.142

• atomic scale. It is known, that the (112) surface energy is relatively high and that the growth speed of [112] is faster than that of other facets [35]. Hence elongated silver wires are generated due to the anisotropy in growth rate. However, anisotropy in growth rate cannot guarantee for the formation

• same crystallographic direction. These observations confirm our understanding of the silver wire growth and support the nutrient-supply-flux induced side branching mechanism in silver wire growth. This branching mechanism is valid when the wire growth has very strong anisotropy and the side faces of

Dry friction of microstructured polymer surfaces inspired by snake skin

• Martina J. Baum,
• Lars Heepe,
• Elena Fadeeva and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 1091–1103, doi:10.3762/bjnano.5.122

• in contact with a smooth glass ball by a microtribometer in two perpendicular directions. The SIMPS exhibited a considerable frictional anisotropy: Frictional coefficients measured along the microstructure were about 33% lower than those measured in the opposite direction. Frictional coefficients

• structural wavelength and the mean width of denticulations. The length of the denticulations on SIMPS is shorter than that of the snake surface, but the overall dimensions of the microstructures are comparable (Table 1). The geometrical anisotropy in form of slopes is present (Figure 2a). The angle in the

• coefficients on the smooth surface and the measurements against to the microstructure of the SIMPS and in the lateral directions (Figure 8). A statistically significant anisotropy was found between the measurement directions (i) “along” versus “against” the microstructure and (ii) “along” versus “lateral” to

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

• parallel, anti-parallel and canting average magnetization states. Results: We give examples of the phase diagrams in terms of anisotropy and coupling strength for two, three and four magnetic layers. Each phase diagrams character is defined by the shape of the magnetic hysteresis profile for a system in an

• anisotropies [1]. A nanomagnet with high shape anisotropy must have some kind of modulation in order to reduce the height of the anisotropy energy barrier. This is typically done through doping in order to reduce the saturation magnetization of the nanomagnet. In recent years amorphous ferromagnetic materials

• have low random anisotropy. In this work we study the magnetic response of linear arrays of nanomagnets to an oscillating magnetic field that is applied at a slight angle from parallel to the longest axis of an individual nanomagnet. A small perturbing magnetic field is also introduced that enables the

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

• ., for the reduction of nitrogen oxides (NxOy) emission in exhausts [15]. A high degree of vertical alignment in the nanotube films (also called ‘carpets’ or ‘forests’) is a key aspect in numerous applications that gain from anisotropy, i.e., supercapacitors [16], counter electrodes [17], structural

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

• data by about a factor of two, both for gnl and (not shown). We attribute this discrepancy to the fact that at zero applied field, any small additional source of pair breaking, such as gap anisotropy, magnetic impurities, spatial profile of the gap due to quasiparticle injection, etc., may contribute

Friction behavior of a microstructured polymer surface inspired by snake skin

• Martina J. Baum,
• Lars Heepe and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 83–97, doi:10.3762/bjnano.5.8

• the skin scales, so called microornamentation [1][4][5][6][7][8][9][10][11][12][13], and specific adaptations of the material architecture of the skin, like highly ordered embedded fibers [14], which can potentially influence material properties [15][16], might contribute to the frictional anisotropy

• different sliding directions within each dimension of pitches, showed a strong frictional anisotropy and strong variation in the occurrence of stick-slip induced vibrations, especially at pitch dimensions of 5 µm and 25 µm. For the smallest dimension of PGMS, less vibrations and a lower frictional

• . In opposite direction, this coefficient was significantly higher (0.32 ± 0.01). Comparison of results obtained in these sliding directions to those obtained in the lateral direction demonstrated the pronounced frictional anisotropy (µ lateral: 0.36 ± 0.02). The occurrence of stick-slip behavior was

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

• Mössbauer spectroscopy in combination with susceptibility measurements it was possible to identify the supertransferred hyperfine field through the oxygen bridges between DyIII and FeIII in a {Fe4Dy2} coordination cluster. The presence of the dysprosium ions provides enough magnetic anisotropy to “block

• ” the hyperfine field that is experienced by the iron nuclei. This has resulted in magnetic spectra with internal hyperfine fields of the iron nuclei of about 23 T. The set of data permitted us to conclude that the direction of the anisotropy in lanthanide nanosize molecular clusters is associated with

• the single ion and crystal field contributions and 57Fe Mössbauer spectroscopy may be informative with regard to the the anisotropy not only of the studied isotope, but also of elements interacting with this isotope. Keywords: anisotropy; dysprosium; iron; Mössbauer spectroscopy; Introduction The

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

• decoration of a graphene sheet by magnetic transition-metal adatoms, utilizing the high in-plane versus out-of-plane magnetic anisotropy energy (MAE), has recently been proposed. This concept is extended in our density-functional-based modeling study by incorporating the influence of the graphene edge on the

• close to the edge, while the opposite is true for the zigzag edge. Additionally, in-plane pinning of the magnetization direction perpendicular to the edge itself is observed for the first time. Keywords: adsorbate; grapheme; graphene quantum dot; magnetic anisotropy; transition metal; Introduction

• graphene with a certain periodic coverage of metal adatoms. A homogeneous distribution of adatoms on a graphene sheet may pose further experimental difficulties, due to the possibility of adatom clustering. The magnetic anisotropy energy (MAE) is known to be profoundly influenced by the symmetry of the