Dynamic behavior of a nematic liquid crystal mixed with CoFe₂O₄ ferromagnetic nanoparticles in a magnetic field

• Emil Petrescu,
• Cristina Cirtoaje and
• Cristina Stan

Beilstein J. Nanotechnol. 2017, 8, 2467–2473, doi:10.3762/bjnano.8.246

• variations of transition thresholds [27][28] or response time [29]. Ferromagnetic nanoparticles are good candidates for LC improvement due to their significant positive magnetic anisotropy and strong anchoring energy [30][31] on a large surface provided by chain clustering. All these effects help the

The interplay between spin densities and magnetic superexchange interactions: case studies of mono- and trinuclear bis(oxamato)-type complexes

• Azar Aliabadi,
• Bernd Büchner,
• Vladislav Kataev and
• Tobias Rüffer

Beilstein J. Nanotechnol. 2017, 8, 2245–2256, doi:10.3762/bjnano.8.224

• shown to be sufficient for this purpose [9], since at Q- and especially at W-band frequencies the powder pattern of the ESR spectrum arising due to the g-factor anisotropy is much better resolved. We demonstrated that the higher the tetrahedral distortion of the CuN2O4 coordination units of type-II

• on Nalkyl donor atoms, which reveal smaller parameters of the associated HF tensor C. Surprisingly the HF tensor D, which is also related to Nalkyl, appears to be similar to A–B. This could be a result of an overestimate of the anisotropy of the HF couplings due to the still somewhat limited

Ta₂N₃ nanocrystals grown in Al₂O₃ thin layers

• Krešimir Salamon,
• Maja Buljan,
• Iva Šarić,
• Mladen Petravić and
• Sigrid Bernstorff

Beilstein J. Nanotechnol. 2017, 8, 2162–2170, doi:10.3762/bjnano.8.215

• important feature of the NPs is their anisotropy. The in-plane dimension (parallel to the surface plane), Dy, is larger than the out-of-plane dimension (perpendicular to the surface plane), Dz, that is, the NPs are slightly elongated in the surface plane. Note that up to 700 °C the morphological properties

Magnetic properties of optimized cobalt nanospheres grown by focused electron beam induced deposition (FEBID) on cantilever tips

• Soraya Sangiao,
• César Magén,
• Darius Mofakhami,
• Grégoire de Loubens and
• José María De Teresa

Beilstein J. Nanotechnol. 2017, 8, 2106–2115, doi:10.3762/bjnano.8.210

• better accuracy, one can also use the value of the saturation field of the nanosphere. For a perfect sphere without crystalline anisotropy, it is only governed by demagnetizing effects and equal to µ0Ms/3. This saturation field is accurately determined from a series of measurement similar to the one

Electronic structure, transport, and collective effects in molecular layered systems

• Torsten Hahn,
• Tim Ludwig,
• Carsten Timm and
• Jens Kortus

Beilstein J. Nanotechnol. 2017, 8, 2094–2105, doi:10.3762/bjnano.8.209

• in the eigenbasis of Hmol (i.e., coherences) vanish if the system is non-magnetic or all magnetic axes (applied magnetic field, magnetization, easy anisotropy axis) are parallel. Then one obtains rate equations for the diagonal components, i.e., for the probabilities of molecular states, where m and

Optical techniques for cervical neoplasia detection

• Tatiana Novikova

Beilstein J. Nanotechnol. 2017, 8, 1844–1862, doi:10.3762/bjnano.8.186

• ., a strong optical anisotropy) when the azimuth of the polarizer was varied [105]. Contrary to that the OSC contrasts in CIN zones, confirmed by following histological analysis of corresponding biopsies, showed no dependence on the azimuth variation. Consequently, CIN zones behaved as an isotropic

• squamous epithelium exhibited strong birefringence (optical index anisotropy), which vanished in precancerous regions even for LSIL. The orientation of the optical axis of retarder became completely random in CIN zones. This effect was attributed to the degeneration of stromal collagen beneath the

Self-assembly of chiral fluorescent nanoparticles based on water-soluble L-tryptophan derivatives of p-tert-butylthiacalix[4]arene

• Pavel L. Padnya,
• Irina A. Khripunova,
• Olga A. Mostovaya,
• Timur A. Mukhametzyanov,
• Vladimir G. Evtugyn,
• Vyacheslav V. Vorobev,
• Yuri N. Osin and
• Ivan I. Stoikov

Beilstein J. Nanotechnol. 2017, 8, 1825–1835, doi:10.3762/bjnano.8.184

• characterized with anisotropy g-factors. The obtained compounds form nanoparticles in water with appreciable chiroptical activity with g-factors reaching 1.89 × 10−4 in the UV region of the spectrum (Supporting Information File 1, Figure S30). Conclusion New water-soluble tetra-substituted lower-rim derivatives

(Metallo)porphyrins for potential materials science applications

• Lars Smykalla,
• Carola Mende,
• Michael Fronk,
• Pablo F. Siles,
• Michael Hietschold,
• Georgeta Salvan,
• Dietrich R. T. Zahn,
• Oliver G. Schmidt,
• Tobias Rüffer and
• Heinrich Lang

Beilstein J. Nanotechnol. 2017, 8, 1786–1800, doi:10.3762/bjnano.8.180

• differences in the number of absorption bands due to symmetry considerations regarding free-base H2TPP(OMe)4 compared to metalated NiTPP(OMe)4 and CuTPP(OMe)4 [16][17]. Additionally, the optical anisotropy of the extinction coefficient determined from VASE in the spectral range of the first absorption band

Charge transfer from and to manganese phthalocyanine: bulk materials and interfaces

• Florian Rückerl,
• Daniel Waas,
• Bernd Büchner,
• Martin Knupfer,
• Dietrich R. T. Zahn,
• Francisc Haidu,
• Torsten Hahn and
• Jens Kortus

Beilstein J. Nanotechnol. 2017, 8, 1601–1615, doi:10.3762/bjnano.8.160

• where they lie face to face. This high degree of order also allowed us to study the anisotropy of the excitations into Co-derived 3d levels in F16CoPc close and far from the interface to MnPc. The corresponding data at the Co 2p absorption edges again show a very clear anisotropy when taken with

Spin-chemistry concepts for spintronics scientists

• Konstantin L. Ivanov,
• Alexander Wagenpfahl,
• Carsten Deibel and
• Jörg Matysik

Beilstein J. Nanotechnol. 2017, 8, 1427–1445, doi:10.3762/bjnano.8.143

• reaction yield on the field strength, but also on the molecular orientation [91], for instance due to the anisotropy of the hyperfine interaction. The orientation dependence is of importance in solids, since in liquids molecules usually tumble so fast that anisotropic spin interactions are averaged out and

Deposition of exchange-coupled dinickel complexes on gold substrates utilizing ambidentate mercapto-carboxylato ligands

• Martin Börner,
• Laura Blömer,
• Marcus Kischel,
• Peter Richter,
• Georgeta Salvan,
• Dietrich R. T. Zahn,
• Pablo F. Siles,
• Maria E. N. Fuentes,
• Carlos C. B. Bufon,
• Daniel Grimm,
• Oliver G. Schmidt,
• Daniel Breite,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Nanotechnol. 2017, 8, 1375–1387, doi:10.3762/bjnano.8.139

• than definitive because these measurements are not the most appropriate for the determination of D-values. It should also be noted that HFEPR experiments for carboxylato-bridged [Ni2L(O2CR)]+ complexes revealed a negative axial magnetic anisotropy parameter (D < 0) with D-values of approximately −0.04

• cm−1, indicative of an easy magnetic anisotropy axis. However, the magnetic anisotropy barrier is too small to allow for sufficient retention of magnetization at finite temperature. The value of J, on the other hand, does not significantly depend on D. Thus, J is unambiguous and provides a correct

3D continuum phonon model for group-IV 2D materials

• Morten Willatzen,
• Lok C. Lew Yan Voon,
• Appala Naidu Gandi and
• Udo Schwingenschlögl

Beilstein J. Nanotechnol. 2017, 8, 1345–1356, doi:10.3762/bjnano.8.136

• anisotropy and flexural modes perpendicular to the layers and can thus be applied to any two-dimensional material. In this paper, we use the model to not only compare the phonon spectra among the group-IV materials but also to study whether these phonons differ from those of a compound material such as

Two-dimensional silicon and carbon monochalcogenides with the structure of phosphorene

• Dario Rocca,
• Ali Abboud,
• Ganapathy Vaitheeswaran and
• Sébastien Lebègue

Beilstein J. Nanotechnol. 2017, 8, 1338–1344, doi:10.3762/bjnano.8.135

• these monolayers were determined using density functional theory. By using accurate hybrid functionals it was found that these materials are semiconductors and span a broad range of bandgap values and types. Similarly to phosphorene, the computed effective masses point to a strong in-plane anisotropy of

• phosphorene very promising for certain applications. Additionaly, phosphorene is characterized by a strong anisotropy in the carrier mobility [14] and ferroelasticity [16]. Recently, some parent compounds to phosphorene have been considered. For example, P–As compounds were studied theoretically and

• computing phonon dispersion curves, in this work we show that carbon and silicon monochalcogenides are dynamically stable in a puckered structure. Additionally, we compute band structures using the quantitatively accurate HSE06 hybrid functional [29] and we evaluate effective masses, whose anisotropy

Near-field surface plasmon field enhancement induced by rippled surfaces

• Mario D’Acunto,
• Francesco Fuso,
• Ruggero Micheletto,
• Makoto Naruse,
• Francesco Tantussi and
• Maria Allegrini

Beilstein J. Nanotechnol. 2017, 8, 956–967, doi:10.3762/bjnano.8.97

• role, in particular whenever the nanostructure morphology shows anisotropy at the local scale. Polarization can induce strong confinement of plasmons in the resonance region in close correlation with the local surface morphology, characterized by a pattern of hills and valleys. As a consequence, an

• considered here is composed of the interplay of patterns made of grooves, hills and valleys showing some degree of anisotropy. Alignment effects induced, for example, by the anisotropic ion bombardment can in fact take place, leading to the occurrence of one preferential direction. The surface plasmon

• ., it is ruled by the geometrical anisotropy. We can say that the applied polarization of the electric field drives the plasmon resonance to be a geometrical polarization. Since the hot spots are strongly dependent on the charge density fluctuations due to rippled surfaces, the effect of the incident

Dispersion of single-wall carbon nanotubes with supramolecular Congo red – properties of the complexes and mechanism of the interaction

• Anna Jagusiak,
• Barbara Piekarska,
• Tomasz Pańczyk,
• Małgorzata Jemioła-Rzemińska,
• Elżbieta Bielańska,
• Barbara Stopa,
• Grzegorz Zemanek,
• Janina Rybarska,
• Irena Roterman and
• Leszek Konieczny

Beilstein J. Nanotechnol. 2017, 8, 636–648, doi:10.3762/bjnano.8.68

• . Birefringence implies anisotropy and ordered arrangement of dye molecules bound to regular, beta-structured amyloid fibrils [29][30]. Congo red molecules self-assemble in water solutions producing supramolecular entities stabilized by π–π interactions between aromatic rings [31][32][33]. Supramolecular Congo

Formation and shape-control of hierarchical cobalt nanostructures using quaternary ammonium salts in aqueous media

• Ruchi Deshmukh,
• Anurag Mehra and
• Rochish Thaokar

Beilstein J. Nanotechnol. 2017, 8, 494–505, doi:10.3762/bjnano.8.53

• (monomers) in presence of quaternary ammonium salts. Hydroxide ions and a magnetic moment of the monomers are essential to induce shape anisotropy in the nanostructures. The cobalt nanoplates are studied in detail, and a growth mechanism based on collision, aggregation, and crystal consolidation is proposed

• of a nanoplate. The study explains, hereto unaddressed, the temporal evolution of complex magnetic nanostructures. These ferromagnetic nanostructures represent an interesting combination of shape anisotropy and magnetic characteristics. Keywords: Brownian motion; cobalt nanoplates; electron

• examined in detail. This observation is in agreement with previous studies that suggest that shape anisotropy is observed only above a certain concentration of hydroxide ions [23][24][29]. EDS measurements of well-formed nanoplates showing the presence of cobalt is are given in Figure S4 (Supporting

Methods for preparing polymer-decorated single exchange-biased magnetic nanoparticles for application in flexible polymer-based films

• Laurence Ourry,
• Delphine Toulemon,
• Souad Ammar and
• Fayna Mammeri

Beilstein J. Nanotechnol. 2017, 8, 408–417, doi:10.3762/bjnano.8.43

• coupling at the F–AF interface (see for instance [16][17][18]), leading to an enhanced effective magnetic anisotropy constant (Keff) and a higher temperature of transition from a magnetically blocked state to a superparamagnetic one (TB) [19][20]. Focusing on such particles, in this work, we propose

Cubic chemically ordered FeRh and FeCo nanomagnets prepared by mass-selected low-energy cluster-beam deposition: a comparative study

• Veronique Dupuis,
• Anthony Robert,
• Arnaud Hillion,
• Ghassan Khadra,
• Nils Blanc,
• Damien Le Roy,
• Florent Tournus,
• Clement Albin,
• Olivier Boisron and
• Alexandre Tamion

Beilstein J. Nanotechnol. 2016, 7, 1850–1860, doi:10.3762/bjnano.7.177

• drastically affects the intrinsic properties of this system by reducing the magnetization in comparison to the bulk. Keywords: bimetallic nanoparticles; magnetic moment and anisotropy; metamagnetic transition; Introduction Magnetic bimetallic nanoparticles (NPs) are very attractive systems not only from a

• -field-cooling (ZFC) and field-cooling (FC) susceptibility curves show a transition from the superparamagnetic to the blocked regime for the as-prepared NPs with a maximum ZFC temperature (Tmax). Tmax is connected to the energy barrier (ΔE = KeffV, with Keff the effective anisotropy constant and V the

• magnetic anisotropy constant. As demonstrated [21], only one set of parameters can fit the three curves at the same time. This “triple fit” method thus reduced the solution range of the different parameters and the uncertainty on their values. Alternating-current magnetic-susceptibility and ferromagnetic

A new approach to grain boundary engineering for nanocrystalline materials

• Shigeaki Kobayashi,
• Sadahiro Tsurekawa and
• Tadao Watanabe

Beilstein J. Nanotechnol. 2016, 7, 1829–1849, doi:10.3762/bjnano.7.176

• Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan, Key Laboratory for Anisotropy and Texture of Materials, Northeastern University, Shenyang 110004, China, Formerly, Tohoku University, Sendai, Japan 10.3762/bjnano.7.176 Abstract A new approach to grain boundary engineering (GBE) for

Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment

• Ann-Kathrin Kleinschmidt,
• Lars Barzen,
• Johannes Strassner,
• Christoph Doering,
• Henning Fouckhardt,
• Wolfgang Bock,
• Michael Wahl and
• Michael Kopnarski

Beilstein J. Nanotechnol. 2016, 7, 1783–1793, doi:10.3762/bjnano.7.171

• Institut für Oberflächen- und Schichtanalytik (IFOS) GmbH, Trippstadter Str. 120, D-67663 Kaiserslautern, Germany 10.3762/bjnano.7.171 Abstract Reflectance anisotropy spectroscopy (RAS) equipment is applied to monitor dry-etch processes (here specifically reactive ion etching (RIE)) of monocrystalline

• sample in order to make RAS control possible. Keywords: broad area semiconductor lasers (BAL); dry-etch monitoring (RIE); precise etch depth control; reflectance anisotropy spectroscopy (RAS); III–V semiconductors; Introduction Reflectance anisotropy/difference spectroscopy (RAS/RDS) [1][2][3][4][5] is

• -known for different etch parameters.) Thus with this highly etch-depth sensitive process a real benefit of on-line control is illustrated. Conclusion Reflectance anisotropy spectroscopy (RAS) can be used to monitor monocrystalline III–V semiconductor sample surfaces in situ during reactive ion etching

Morphology of SiO₂ films as a key factor in alignment of liquid crystals with negative dielectric anisotropy

• Volodymyr Tkachenko,
• Antigone Marino,
• Eva Otón,
• Noureddine Bennis and
• Josè Manuel Otón

Beilstein J. Nanotechnol. 2016, 7, 1743–1748, doi:10.3762/bjnano.7.167

• , we studied the optical anisotropy of thin SiO2 films by generalized ellipsometry as a function of deposition angle. The columnar SiO2 structure orientation measured by a noninvasive ellipsometry technique is reported for the first time, and its morphology influence on the LC alignment is demonstrated

• for large deposition angles. Keywords: anisotropy; ellipsometry; liquid crystal alignment; morphology; thin film; Introduction Thin films of SiO2 and SiOx obtained by oblique deposition are commonly used as alignment layers for liquid crystal (LC) displays [1][2][3][4][5][6][7]. Several alignments

• control of pretilt in VAN cells is essential in many applications, as it affects display contrast and response time [2][6][7]. Pretilt depends on a number of factors such as chemical interaction forces between LC molecules and an alignment film, dielectric anisotropy of the LC, and film morphology. Many

Surface-enhanced infrared absorption studies towards a new optical biosensor

• Lothar Leidner,
• Julia Stäb,
• Jennifer T. Adam and
• Günter Gauglitz

Beilstein J. Nanotechnol. 2016, 7, 1736–1742, doi:10.3762/bjnano.7.166

• wavelength-dependent backscattering, part of which is directed to the detector. The spherical nanoparticles are responsible for a relatively weak water band. When anisotropy is added to a nanoparticle, the optical properties change dramatically [15]. Therefore, as a last step of the experiment anisotropy is

• . The increase of the water absorption band in the case of aggregated nanoparticles may have two explanations: first, the SEIRA effect is enhanced when nanoparticles aggregate (addition of anisotropy, see [15]); second, the backscattering cross section is increased. Peak shift A further interesting

Properties of Ni and Ni–Fe nanowires electrochemically deposited into a porous alumina template

• Alla I. Vorobjova,
• Dmitry L. Shimanovich,
• Kazimir I. Yanushkevich,
• Sergej L. Prischepa and
• Elena A. Outkina

Beilstein J. Nanotechnol. 2016, 7, 1709–1717, doi:10.3762/bjnano.7.163

• ; Introduction Arrays of vertically arranged metallic NWs have attracted a lot of attention due to their shape anisotropy and extremely large surface area. The combination of this unique structure with uncommon magnetic, optical and transport properties can be used to develop novel functional nanomaterials for

• electrochemical deposition of metals, alloys and multilayer compositions into PA templates [27][28][29]. Some unique magnetic phenomena, such as GMR effect, magnetic crystalline anisotropy, magneto-optical properties depend directly on morphological characteristics (primarily the aspect ratio) and the crystal

Analysis of self-heating of thermally assisted spin-transfer torque magnetic random access memory

• Austin Deschenes,
• Sadid Muneer,
• Mustafa Akbulut,
• Ali Gokirmak and
• Helena Silva

Beilstein J. Nanotechnol. 2016, 7, 1676–1683, doi:10.3762/bjnano.7.160

• magnetic random access memory (STT-MRAM). Proposed heating methods include modified material stack compositions that result in increased self-heating or external heat sources. In this work we analyze the self-heating process of a standard perpendicular magnetic anisotropy STT-MRAM device through numerical

• temperatures of 360 K to 523 K, through manipulation of the material stack [3]. However, changing the material stack compromises the desired anisotropy levels and external heat sources impact device density. Thus, these methods for thermal assistance can be considered limited in their potential. In this work

• we perform an electro-thermal analysis of the self-heating process for a standard perpendicular magnetic anisotropy STT-MRAM device (Figure 1) to understand the relative contributions of the different heat mechanisms involved and the effect of external device parameters such as passivation material

Biomechanics of selected arborescent and shrubby monocotyledons

• Tom Masselter,
• Tobias Haushahn,
• Samuel Fink and
• Thomas Speck

Beilstein J. Nanotechnol. 2016, 7, 1602–1619, doi:10.3762/bjnano.7.154

• investigations on the branching mechanics of “woody” monocots. In addition, these data can be incorporated in finite element models at cell and tissue level that mirror the anisotropy and the stress–strain behaviour of the investigated plants at stem level [6][7]. This allows for a deepened understanding of the