Tunable longitudinal modes in extended silver nanoparticle assemblies

• Serene S. Bayram,
• Klas Lindfors and
• Amy Szuchmacher Blum

Beilstein J. Nanotechnol. 2016, 7, 1219–1228, doi:10.3762/bjnano.7.113

• these unprecedented anisotropic structures. Our results show a correlation between the chain nature of the assembly and the generation of spectral anisotropy. Deuterating the ligand further enhances the anisotropic signal by triggering more compact aggregates and reveals the importance of solvent

• -mediated assembly of AgNPs requires prolonged incubation times without generating intense anisotropy [25]. Herein, we report a “green & cheap” kit for the facile and quick assembly of AgNPs into highly anisotropic structures that reveal chain-like, branched networks as well as dense aggregates mediated by

• -defined, distinct longitudinal band implies that the silver nanoparticles are forming anisotropic aggregates. For cysteine and DTT, at very high ligand-to-nanoparticle ratios, the transverse and longitudinal collapse into a single very broad resonance, which indicates a loss of structural anisotropy in

Customized MFM probes with high lateral resolution

• Óscar Iglesias-Freire,
• Miriam Jaafar,
• Eider Berganza and
• Agustina Asenjo

Beilstein J. Nanotechnol. 2016, 7, 1068–1074, doi:10.3762/bjnano.7.100

• ] to improve the detection of small domains. One can also find the use of nanomagnets with high anisotropy as MFM probes [13] and different approaches to control the final domain at the tip apex [14][15], seeking best sensitivity or resolution. However, the easiest interpretation of the results is

• influence of the dominating shape anisotropy (as deduced from the cross-tie domain walls [22] seen in Figure 1c), in agreement with the macroscopic hysteresis loops measured at room temperature by VSM (Figure 1d). A high remanent magnetization of 82% of the saturation value is found when an IP field is

• applied. This, together with the shape anisotropy induced by the pyramidal tip, forces the magnetic moments to remain mainly oriented along the pyramid surface. Nevertheless, the orientation of the spins at the apex will depend on the apex shape and on the way the cobalt layer covers it. Results and

Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

• Julia Körner,
• Christopher F. Reiche,
• Thomas Gemming,
• Bernd Büchner,
• Gerald Gerlach and
• Thomas Mühl

Beilstein J. Nanotechnol. 2016, 7, 1033–1043, doi:10.3762/bjnano.7.96

• the anisotropy field of the sample Ha, so Equation 2 reads: This equation can be used as a good approximation for the iron-filled carbon nanotube samples which are presented in this publication. However, please note that other samples might exhibit more complex magnetic configurations, as for example

Development of highly faceted reduced graphene oxide-coated copper oxide and copper nanoparticles on a copper foil surface

• Rebeca Ortega-Amaya,
• Yasuhiro Matsumoto,
• Andrés M. Espinoza-Rivas,
• Manuel A. Pérez-Guzmán and
• Mauricio Ortega-López

Beilstein J. Nanotechnol. 2016, 7, 1010–1017, doi:10.3762/bjnano.7.93

• , as explained by Meltzman et al. [40], the presence of carbon layers at the surface, modifies the anisotropy giving rise to the appearance of other facets. Conclusion We describe the formation of faceted core–shell Cu2O-rGO and Cu-rGO nanoparticles on the surface of a Cu foil by annealing foil

Phenalenyl-based mononuclear dysprosium complexes

• Yanhua Lan,
• Andrea Magri,
• Olaf Fuhr and
• Mario Ruben

Beilstein J. Nanotechnol. 2016, 7, 995–1009, doi:10.3762/bjnano.7.92

• individual spins through dipolar exchange in such a simple molecular unit. As highlighted recently in many work [8][9][10][11][12][13][14], the determining factor in the construction of SMMs and single-ion magnets (SIMs) and in the control of the single-axial anisotropy is related to the symmetry at the

• individual Ln sites along with the nature of the ligand field. Owing to a very strong Ising-type uniaxial anisotropy of the metal ion, dysprosium containing compounds are extensively studied and have been found to have the most promising slow-relaxation behavior. Typical examples are [Dy(acac)3(H2O)2] [8

• , respectively. However, due to the incomplete saturation of the magnetization, a residual slope is observed at high fields indicating the presence of magnetic anisotropy in the material [48][49]. Moreover, no hysteresis effect is observed in all three cases under these conditions. Dynamic magnetic properties As

Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Gianluigi Zito,
• Teresa Cacace,
• Antigone Marino,
• José M. Otón and
• Morten A. Geday

Beilstein J. Nanotechnol. 2016, 7, 825–833, doi:10.3762/bjnano.7.74

• orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules. Keywords: Anchoring; carbon nanotubes; impedance; liquid crystal; negative anisotropy; Raman spectroscopy; reorientation; single-wall CNTs

• director lies in the plane of the cell surfaces, while in homeotropic alignment the director orients perpendicular to the plane of the cell surfaces. LCs feature, amongst others, electrical, magnetic, and optical (birefringence) anisotropy properties. In the absence of an external field, the LC orientation

• along the long axis (which roughly matches the director orientation) or perpendicular to the long axis. They are customarily classified as positive and negative LCs according to their dielectric anisotropy [6]. In a positive LC material, the dielectric constant along the director is larger than the

Microscopic characterization of Fe nanoparticles formed on SrTiO₃(001) and SrTiO₃(110) surfaces

• Miyoko Tanaka

Beilstein J. Nanotechnol. 2016, 7, 817–824, doi:10.3762/bjnano.7.73

• plane. This type of modified Wulff construction, which takes into account the particle–substrate interaction, is denominated as the Winterbottom construction [58]. The Winterbottom theory describes the dependence of the particle shape upon the anisotropy of the surface energy of the particle and upon

Magnetic switching of nanoscale antidot lattices

• Ulf Wiedwald,
• Joachim Gräfe,
• Kristof M. Lebecki,
• Maxim Skripnik,
• Felix Haering,
• Gisela Schütz,
• Paul Ziemann,
• Eberhard Goering and
• Ulrich Nowak

Beilstein J. Nanotechnol. 2016, 7, 733–750, doi:10.3762/bjnano.7.65

• spherical masks for the production of magnetic antidot lattices. In magnetic antidot films, the nanoscale periodic structure of holes introduces an in-plane shape anisotropy to the otherwise isotropic in-plane properties of polycrystalline or amorphous thin films. Additionally, the holes may act as

• magnetic properties of in-plane magnetized antidot films. Integral magnetometry averaging over all in-plane angles of the antidots with respect to the external field proves that the system is highly dominated by the local shape anisotropy introduced by the hole sites. We identify two distinct switching

• solve partial differential equations numerically [26]. Calculations are performed by minimizing the total magnetic energy of the system, containing contributions from the exchange energy, the anisotropy energy, the demagnetizing field, and the Zeeman energy [27]. We comprise the distributions of the

Cantilever bending based on humidity-actuated mesoporous silica/silicon bilayers

• Christian Ganser,
• Gerhard Fritz-Popovski,
• Roland Morak,
• Parvin Sharifi,
• Benedetta Marmiroli,
• Barbara Sartori,
• Heinz Amenitsch,
• Thomas Griesser,
• Christian Teichert and
• Oskar Paris

Beilstein J. Nanotechnol. 2016, 7, 637–644, doi:10.3762/bjnano.7.56

• directional movement by using swelling of polymers in combination with controllable anisotropy [10]. However, to our knowledge such concepts have not been used so far to create ceramic or metallic bilayer structures, which would have the advantage of their applicability at higher temperatures and in harsh

Correlative infrared nanospectroscopic and nanomechanical imaging of block copolymer microdomains

• Benjamin Pollard and
• Markus B. Raschke

Beilstein J. Nanotechnol. 2016, 7, 605–612, doi:10.3762/bjnano.7.53

• , anisotropy within a single PMMA region itself could affect the degree of intermolecular coupling, manifesting in linewidth changes within a single microdomain. The modulus image (Figure 3c) shows contrast from the differing mechanical properties of PMMA and PS. We observe values around 1–2 GPa in PMMA

Orientation of FePt nanoparticles on top of a-SiO₂/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size

• Martin Schilling,
• Paul Ziemann,
• Zaoli Zhang,
• Johannes Biskupek,
• Ute Kaiser and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2016, 7, 591–604, doi:10.3762/bjnano.7.52

• transmission electron microscopy (HRTEM); nanoparticles; reflection high-energy electron diffraction (RHEED); solid-phase epitaxy; texture; Introduction Due to their attractive catalytic properties for oxygen reduction reactions (ORR) [1][2] as well as their high magnetocrystalline anisotropy energy density

Active multi-point microrheology of cytoskeletal networks

• Tobias Paust,
• Tobias Neckernuss,
• Lina Katinka Mertens,
• Ines Martin,
• Michael Beil,
• Paul Walther,
• Thomas Schimmel and
• Othmar Marti

Beilstein J. Nanotechnol. 2016, 7, 484–491, doi:10.3762/bjnano.7.42

• response motion, which leads to a decreasing SNR. In the case of 1 mM Mg2+ this results in a dramatic increase of calculation errors. The exemplary transfer matrices calculated for particles at a distance of 3 µm for all three cases show that the system is not isotropic. This anisotropy of the assembled

Organized films

• Maurizio Canepa and
• Helmuth Möhwald

Beilstein J. Nanotechnol. 2016, 7, 406–408, doi:10.3762/bjnano.7.35

• microscopy and Brewster angle microscopy [4][5][6][7] were successfully employed to show that Langmuir monolayers exhibit an interesting domain structure on the micrometer scale with peculiar features due to the anisotropy of the interface. Surface X-ray diffraction revealed a multitude of ordered and

Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

• Tuan Anh Pham,
• Andreas Schreiber,
• Elena V. Sturm (née Rosseeva),
• Stefan Schiller and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2016, 7, 351–363, doi:10.3762/bjnano.7.32

• anisotropy in shape and possible properties. However, nanoparticle (NP) assembly leading to one-dimensional (1D) superstructures or arrays has received less attention compared to their two- or three-dimensional equivalents [2]. The NP assembly can be conducted in a template-based or template-free way. In

• and Figure 5). The field-cooling (FC) curves exhibit a slight steeper slope in the hybrid material (Figure 10D). However, the overall trend in the FC curves for both samples is similar. The effective magnetic anisotropy constant (Keff) can be calculated using following expression: Keff = (25·kB·Tb)/V

• due to the broken symmetry at the surface or interface of the NPs, which can enhance the surface anisotropy and cause the increased effective values of K [40]. The fiber-like hybrid material shows Keff close to the bulk material value, which indicates the stabilization of the surface spin compared to

Hydration of magnesia cubes: a helium ion microscopy study

• Ruth Schwaiger,
• Johannes Schneider,
• Gilles R. Bourret and
• Oliver Diwald

Beilstein J. Nanotechnol. 2016, 7, 302–309, doi:10.3762/bjnano.7.28

• crystalline organic polymers such as polyimides that were grown by hydrothermal crystallization [37][38]. Independent of the chemical composition, nucleation is initiated at screw dislocations. Further crystallization proceeds non classically due to a strong growth anisotropy and different attachment energies

Single-molecule magnet behavior in 2,2’-bipyrimidine-bridged dilanthanide complexes

• Wen Yu,
• Frank Schramm,
• Eufemio Moreno Pineda,
• Yanhua Lan,
• Olaf Fuhr,
• Jinjie Chen,
• Hironari Isshiki,
• Wolfgang Wernsdorfer,
• Wulf Wulfhekel and
• Mario Ruben

Beilstein J. Nanotechnol. 2016, 7, 126–137, doi:10.3762/bjnano.7.15

• date, the largest anisotropy barrier observed in a transition metal SMM is 226 cm−1 in the Fe(II) complex [Fe(C(SiMe3)3)2]− [10]. Recently, molecular compounds employing lanthanide ions led to a considerable increase in strength of molecular magnets due to the observation of the SMM character at the

• single-ion level [11][12]. SMMs based on 4f ions possess larger thermal energy barriers for magnetization reversal caused by their large single-ion magnetic anisotropy, which originates from spin–orbit coupling and crystal-field splitting of the 4f ions. Technological and structural development of

• -ion magnetic anisotropy) with a 2,2’-bipyrimidine bridging ligand. The observed SMM character, with hysteresis loops observed as high as 5 K, make this class of bipyrimidine-bridged dilanthanide complexes promising systems to be sublimated onto surfaces. In this way, it is possible to study their

Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine

• Benjamin Siegert,
• Andrea Donarini and
• Milena Grifoni

Beilstein J. Nanotechnol. 2015, 6, 2452–2462, doi:10.3762/bjnano.6.254

• splitting of former degenerate levels and a magnetic anisotropy, which can be captured by an effective low-energy spin Hamiltonian. We show that scanning tunneling microscopy-based magnetoconductance measurements can yield clear signatures of both these SOI-induced effects. Keywords: anisotropy; copper

• in establishing magnetic anisotropy in high-spin molecular magnets [1], and it is quite generally expected in metalorganic compounds. Effective spin-Hamiltonians are commonly used to describe this anisotropy, and usually capture well the low energy properties of these systems [1][2][3]. Such

• effective Hamiltonians have been derived microscopically for widely studied molecular magnets such as Fe8, Fe4 and Mn12 [4]. Recently, magnetic anisotropy effects could be directly probed by magnetotransport spectroscopy for Fe4 in quantum-dot setups [5][6]. An interesting question is hence if other classes

Surface-enhanced Raman scattering by colloidal CdSe nanocrystal submonolayers fabricated by the Langmuir–Blodgett technique

• Alexander G. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Volodymyr M. Dzhagan,
• Ovidiu D. Gordan,
• Sergey L. Veber,
• Cameliu Himcinschi,
• Alexander V. Latyshev and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2015, 6, 2388–2395, doi:10.3762/bjnano.6.245

• orders of magnitude depending on the gap size) than the field located near a single metal nanocluster or a metal surface [33]. SERS enhancement benefits from the implementation of this experimental geometry. In particular, it allows the influence of the spatial confinement and the structure anisotropy on

• axis is 30% weaker than that for the orthogonal polarization. This effect could be explained by the resonant absorption of the laser light by the longitudinal plasmon near Au dimers that reduces the Raman scattering signal from the underlying Si. The observed anisotropy of both CdSe- and Si-related

An adapted Coffey model for studying susceptibility losses in interacting magnetic nanoparticles

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2015, 6, 2173–2182, doi:10.3762/bjnano.6.223

• dipolar interactions among the nanoparticles: The magnetic moments of the i-th and j-th nanoparticle can be indicated with μi and μj, respectively, both with uniaxial anisotropy. Since nanoparticle i has a dipole–dipole magnetostatic interaction with all the other nanoparticles, the magnetic dipolar

• vectors of the magnetic moments of the nanoparticles i and j, respectively, and μ0 is the magnetic permeability of vacuum. Due to clinical limitations on the amplitude of the external magnetic field Hext [4][6][10], the anisotropy axes of the spherical nanoparticles are not perfectly aligned to the

• external magnetic field. Due to the internal dipolar magnetic field, a local magnetic field appears in nanoparticle according to Equation 9. This local magnetic field is, in general, not oriented along the anisotropy axis of each particle. For handling this situation, we adapted the Coffey analytical model

Focused particle beam-induced processing

• Michael Huth and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2015, 6, 1883–1885, doi:10.3762/bjnano.6.191

• article by Gian Carlo Gazzadi and Stefano Frabboni [6]. This leads into the important application field of magnetic nanostructures obtained by FEBID. Luis Rodríguez and coworkers present a detailed study on the influence of shape anisotropy and surface oxidation on the magnetization reversal of thin, iron

A simple method for the determination of qPlus sensor spring constants

• John Melcher,
• Julian Stirling and
• Gordon A. Shaw

Beilstein J. Nanotechnol. 2015, 6, 1733–1742, doi:10.3762/bjnano.6.177

• ]. However, qPlus sensors violate several of the assumptions inherent in this approach (see Figure 1). In particular, the cross-section of the tine is not rectangular, but rather includes a peaked ridge resulting from anisotropy in the crystal etching process [30]. The assumption of axial uniformity is

Radiation losses in the microwave K_u band in magneto-electric nanocomposites

• Talwinder Kaur,
• Sachin Kumar,
• Jyoti Sharma and
• A. K. Srivastava

Beilstein J. Nanotechnol. 2015, 6, 1700–1707, doi:10.3762/bjnano.6.173

• interesting material with variable properties and a large anisotropy field having a magnetic resonance in the range of 2–52 GHz. Also, at the nano-scale, its optical properties [19], magnetic properties [20][21], piezo-electric properties [22], photocatalytic properties [23], gas-sensing properties [24

• ], electrical properties, dielectric properties [25][26], and mechanical properties [27] are better than those of the bulk material. Hexaferrite is also extensively studied by researchers for radiation absorption which is based on magnetic resonance phenomena because of the anisotropy field [10][28]. In this

• initial permeability, line width, domain-wall displacement and coercive force. The new absorption mechanism arises from the reduced particle size in nanometre range. The natural resonance frequency of barium hexaferrite lies in the range of 50–60 GHz because of the large magneto-crystalline anisotropy and

Structural and magnetic properties of iron nanowires and iron nanoparticles fabricated through a reduction reaction

• Marcin Krajewski,
• Wei Syuan Lin,
• Hong Ming Lin,
• Katarzyna Brzozka,
• Sabina Lewinska,
• Natalia Nedelko,
• Anna Slawska-Waniewska,
• Jolanta Borysiuk and
• Dariusz Wasik

Beilstein J. Nanotechnol. 2015, 6, 1652–1660, doi:10.3762/bjnano.6.167

• identical, this observation is surprising at the first moment. In general, the effective anisotropy of the nanowires should be much higher due to the high uniaxial shape anisotropy, which is increased by the magnetocrystalline anisotropy with the easy axis oriented along the wire length caused by the

• application of the external magnetic field during the fabrication process. This indicates that during analysis of the hysteresis parameters it is also needed to consider the possible mechanisms of magnetization reversal besides the impact of simple anisotropy. According to the TEM measurements, the

• between them. These interactions result in the strong uniaxial shape anisotropy with the easy axis of magnetization parallel to the length of the wires. This stabilizes the magnetization distributions and causes that the squareness ratio (MR/Ms) is higher in the studied nanowires. Besides that, the

Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

• Xiaoxing Ke,
• Carla Bittencourt and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2015, 6, 1541–1557, doi:10.3762/bjnano.6.158

• anisotropy of the atomic displacement threshold [32][41][42]. The scattering geometry naturally contributes to the variation of the knock-on threshold depending on the nanotube diameter [33]. As shown in Figure 3a, CNTs invariably have a lower knock-on threshold than graphene, whereas the CNTs of smaller

Influence of the shape and surface oxidation in the magnetization reversal of thin iron nanowires grown by focused electron beam induced deposition

• Luis A. Rodríguez,
• Lorenz Deen,
• Rosa Córdoba,
• César Magén,
• Etienne Snoeck,
• Bert Koopmans and
• José M. De Teresa

Beilstein J. Nanotechnol. 2015, 6, 1319–1331, doi:10.3762/bjnano.6.136

• producing the magnetization reversal. Most of magnetic devices work by producing a voltage output when the magnetization reversal occurs. In the case of cobalt deposits, it was previously found that the coercive field is governed by shape anisotropy [24] due to the polycrystalline microstructure [25], and

• valve in the GIS and had to be optimized in order to obtain deposits exhibiting ferromagnetic properties with suitable shape anisotropy. In these experiments, the nominal turbopump speed is 260 L/s for nitrogen gas. When the leak valve is opened, the chamber pressure increases. The chamber pressure is

• decreased to the range from 3 × 10−6 to 4 × 10−6 mbar, the deposits did not show the granular structure and the magnetization reversal was found to be dominated by shape anisotropy (see next section). In situ compositional analysis by energy dispersive X-ray spectroscopy (EDS) indicated that the Fe content