Ferromagnetic behaviour of ZnO: the role of grain boundaries

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

Beilstein J. Nanotechnol. 2016, 7, 1936–1947, doi:10.3762/bjnano.7.185

• SQUID interferometer (Quantum Design MPMS-7 and MPMS-XL) in the external magnetic field applied parallel to the sample plane. The diamagnetic signal from a sample holder and a substrate was accurately subtracted from the magnetization curves. In Figure 3 the magnetization curves are plotted for pure ZnO

• method. Magnetization Js (in units of 10−3 µB/f.u.) as a function of the applied external magnetic field for pure zinc oxide films and zinc oxide films doped with 0.1 and 10 atom % Mn at room temperature. Reproduced with permission from [7], copyright 2009 American Physical Society. Dependence of

Thickness-modulated tungsten–carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields

• Ismael García Serrano,
• Javier Sesé,
• Isabel Guillamón,
• Hermann Suderow,
• Sebastián Vieira,
• Manuel Ricardo Ibarra and
• José María De Teresa

Beilstein J. Nanotechnol. 2016, 7, 1698–1708, doi:10.3762/bjnano.7.162

• Physical Properties Measurement System (PPMS) from Quantum Design. In the following, it is assumed that in our range of measurements the magnetic induction inside the sample, B, is equal to μ0H, with μ0 being the vacuum permeability and H being the external magnetic field. At the magnetic fields and

Microwave synthesis of high-quality and uniform 4 nm ZnFe₂O₄ nanocrystals for application in energy storage and nanomagnetics

• Christian Suchomski,
• Ben Breitung,
• Ralf Witte,
• Michael Knapp,
• Sondes Bauer,
• Tilo Baumbach,
• Christian Reitz and
• Torsten Brezesinski

Beilstein J. Nanotechnol. 2016, 7, 1350–1360, doi:10.3762/bjnano.7.126

• and without an external magnetic field. Table 1 summarizes the fitted parameters, which agree with the ratio of tetrahedral to octahedral Fe in the partially inverted spinel structure from XPS. In addition, Figure 4 confirms that all Fe ions are in the Fe(III) state. This is also corroborated by the

Multiwalled carbon nanotube hybrids as MRI contrast agents

• Nikodem Kuźnik and
• Mateusz M. Tomczyk

Beilstein J. Nanotechnol. 2016, 7, 1086–1103, doi:10.3762/bjnano.7.102

• its abundance and very strong signals in NMR. For this reason, further consideration will focus on this nuclide. In a high external magnetic field B0 the nuclear spins orient along field lines. Slightly more than half of the vectors are directed along the field, while the rest are directed in the

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

• external magnetic field is applied to the setup, the magnetic interaction of the sample with the field alters the resonance frequency of the cantilever by creating a torque [3]. The resulting frequency shift can be used as measurement signal to derive information on the properties of the sample. In most

• frequency of the cantilever. The magnetic interaction between sample and external magnetic field acts as the additional spring constant Δk, altering the resonance frequency of the cantilever. The frequency shift Δf induced by these interactions can be derived from Equation 1 as: In the case of cantilever

• magnetometry, Δk does not only depend on the interaction of the magnetic moment m of the sample with the external magnetic field H but also on the effective length of the cantilever Leff [6][7]. Furthermore, by assuming a simple Stoner–Wohlfarth single domain particle, the magnetic interaction is related to

Synthesis of cobalt nanowires in aqueous solution under an external magnetic field

• Xiaoyu Li,
• Lijuan Sun,
• Hu Wang,
• Kenan Xie,
• Qin Long,
• Xuefei Lai and
• Li Liao

Beilstein J. Nanotechnol. 2016, 7, 990–994, doi:10.3762/bjnano.7.91

• pressures, cobalt nanowires were synthesized by chemical reduction in aqueous solution with the assistance of polyvinylpyrrolidone (PVP) as surfactant under moderate conditions for the first time, while an external magnetic field of 40 mT was applied. Uniform linear cobalt nanowires with relatively smooth

• surfaces and firm structure were obtained and possessed an average diameter of about 100 nm with a coating layer of PVP. By comparison, the external magnetic field and PVP were proven to have a crucial influence on the morphology and the size of the synthesized cobalt nanowires. The prepared cobalt

• . Keywords: aqueous solution; cobalt nanowires; external magnetic field; magnetic properties; surfactant; Findings In recent years, cobalt nanowires, as a ferromagnetic material, have attracted considerable attention due to their outstanding magnetic properties and excellent performance in applications in

Thickness dependence of the triplet spin-valve effect in superconductor–ferromagnet–ferromagnet heterostructures

• Daniel Lenk,
• Vladimir I. Zdravkov,
• Jan-Michael Kehrle,
• Günter Obermeier,
• Aladin Ullrich,
• Roman Morari,
• Hans-Albrecht Krug von Nidda,
• Claus Müller,
• Mikhail Yu. Kupriyanov,
• Anatolie S. Sidorenko,
• Siegfried Horn,
• Rafael G. Deminov,
• Lenar R. Tagirov and
• Reinhard Tidecks

Beilstein J. Nanotechnol. 2016, 7, 957–969, doi:10.3762/bjnano.7.88

• applying an external magnetic field parallel to the layers of the heterostructure and exploiting the intrinsic perpendicular easy-axis of the magnetization of the Cu41Ni59 thin film in conjunction with the exchange bias between CoOx and Co. The magnetic configurations are confirmed by superconducting

• superconductor. We should remark, that strictly obeying the definition of Tc0, it can not be defined for the heterostructures of the present work, because magnetic material is present. Here it is used to identify the transition temperature in zero external magnetic field. For a two-dimensional and a three

• ) indicate the values of α for a two and a three-dimensional superconductor according to the GL-theory, respectively. Superconducting transition temperature, Tc0, in zero external magnetic field as a function of the F1 = Cu41Ni59 layer thickness dF1 = dCuNi. While the solid squares in (a) show experimental

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

• conducted under an external magnetic field. After lyophilization of the reaction mixture, fiber-like structures in the micrometer range are obtained. The TEM investigation demonstrates networked structures of Fe3O4 and CoFe2O4 NPs. The magnetic measurements reveal a superparamagnetic character for the Fe3O4

• Information File 1. The water-dispersible, mercaptosuccinic acid stabilized Fe3O4 NP solution was aligned in an external magnetic field parallel to the sample. After the protein addition, Hcp1_cys3 interconnected the NPs, which results in a fibrous bio-hybrid structure. In Figure 8, SEM with EDX analysis and

• TEM images (Figure S5, Supporting Information File 1). These results indicate that the prealignment of Fe3O4 NPs in an external magnetic field is essential for the linear arrangement of the NPs chain formation. On the other hand, TEM investigations of the hybrid material show a network of magnetite

Simultaneous cancer control and diagnosis with magnetic nanohybrid materials

• Reza Saadat and
• Franz Renz

Beilstein J. Nanotechnol. 2016, 7, 121–125, doi:10.3762/bjnano.7.14

• -analogue Ga-DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complexes were synthesized and linked to Fe3O4 MNP. In this manner it is possible to transport the PET tracer with an external magnetic field right to the target location. The functionalized MNP are linked to each other via

Controlled graphene oxide assembly on silver nanocube monolayers for SERS detection: dependence on nanocube packing procedure

• Martina Banchelli,
• Bruno Tiribilli,
• Roberto Pini,
• Luigi Dei,
• Paolo Matteini and
• Gabriella Caminati

Beilstein J. Nanotechnol. 2016, 7, 9–21, doi:10.3762/bjnano.7.2

• [16] whereas more recently external magnetic field were employed to dynamically control the interparticle spacing of a nanoparticle monolayer at the hexane/water interface [17]; however, the fabrication of controllable hot spots still remains a remarkable challenge. The outstanding SERS capability of

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

• the substrate). This quantum dot configuration should be favourable to experimentally probe SOI splittings and magnetic anisotropies when an external magnetic field is applied to the system, in analogy to the experiments in [6]. Indeed, we demonstrate that experimentally resolvable SOI splitting

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

• nanoparticles is strongly affected by the choice of some parameters such as the amplitude and the frequency of the external magnetic field [1][2]. Typical parameters of AC magnetic fields are frequencies between 100 and 500 kHz with amplitudes ≤30 kA/m [2][3]. A recent investigation in humans resulted in an

• suitable for use in hyperthermia, it is of interest to establish the conditions providing a sufficiently high SLP in an alternating external magnetic field of moderate amplitude Hext and frequency f [5]. The latest researches suggest that the so-called “hard-magnetic nanoparticles” are a more reliable

• nanoparticle causes changes in the orientation of its magnetization [16]. At the limit between hysteretic and superparamagnetic regime, under biomedical conditions of amplitude and frequency of the external magnetic field, susceptibility losses in magnetic colloids can be described by linear response theory

Self-assembly mechanism of Ni nanowires prepared with an external magnetic field

• Xiaoyu Li,
• Hu Wang,
• Kenan Xie,
• Qin Long,
• Xuefei Lai and
• Li Liao

Beilstein J. Nanotechnol. 2015, 6, 2123–2128, doi:10.3762/bjnano.6.217

• aqueous solution under an external magnetic field. The self-assembly mechanism was investigated in detail. The results indicate that the self-assembly process of Ni nanowires consists of three stages: nucleation and growth, ordered alignment and self-assembly, and deposition on the surface and gaps

• magnetic field. Keywords: chemical reduction; external magnetic field; Ni nanoparticles; Ni nanowires; self-assembly mechanism; Introduction For the past decades, ferromagnetic (e.g., Fe, Co, Ni) nanowires have raised considerable attention due to their application prospects in magnetic, optoelectronic

• cobalt nanowires using a gamma irradiation technique under an external magnetic field. Li et al. [15] synthesized nickel chains under a weak magnetic field by hydrazine reduction in ethylene glycol. Smooth Ni nanowires were prepared by Hu et al. [16] under a stronger magnetic field. Soumare et al. [17

Paramagnetism of cobalt-doped ZnO nanoparticles obtained by microwave solvothermal synthesis

• Jacek Wojnarowicz,
• Sylwia Kusnieruk,
• Tadeusz Chudoba,
• Stanislaw Gierlotka,
• Witold Lojkowski,
• Wojciech Knoff,
• Malgorzata I. Lukasiewicz,
• Bartlomiej S. Witkowski,
• Anna Wolska,
• Marcin T. Klepka,
• Tomasz Story and
• Marek Godlewski

Beilstein J. Nanotechnol. 2015, 6, 1957–1969, doi:10.3762/bjnano.6.200

• range T = 5–200 K at an external magnetic field of up to H = 0.5 kOe. SEM images of ZnO nanopowders in their as-produced (before annealing) state: (a) undoped, (b) doped with 1 mol % of Co2+, (c) 5 mol % of Co2+, (d) 10 mol % of Co2+, and (e) 15 mol % of Co2+ ions. SEM images of annealed ZnO nanopowders

• K-edge for the as-synthesized NP samples. Comparison of the Fourier transformations of EXAFS oscillations measured at the Co K-edge for Zn1−xCoxO NPs and the reference Zn1−xCoxO layer grown by ALD for samples before annealing. The magnetization dependence on the external magnetic field: (a) for as

Magnetic reversal dynamics of a quantum system on a picosecond timescale

• Nikolay V. Klenov,
• Alexey V. Kuznetsov,
• Igor I. Soloviev,
• Sergey V. Bakurskiy and
• Olga V. Tikhonova

Beilstein J. Nanotechnol. 2015, 6, 1946–1956, doi:10.3762/bjnano.6.199

• field sources for fast qubit control. However, the important features of the flux qubit dynamics under an external magnetic field have still not been studied in detail, especially regarding the initial state preparation and logical operations performed with the RSFQ-bit circuits. In this context, the

• optimization of the magnetization reversal on the shortest timescale possible is highly relevant. In this work, we investigate the dynamics of a magnetic system under an external magnetic field and focus on the achievement of a short magnetization reversal duration down to the picosecond timescale. The typical

• system and HX(t) is the external magnetic field that is considered in two different forms: as an oscillating or short but unipolar magnetic pulse. We consider a simple two-level magnetic quantum system where its state is described by the nonstationary wavefunction as: Here E1 and E2 are the energies of

Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe₃O₄ nanocomposites as a promising, nontoxic system for biomedical applications

• Hanieh Shirazi,
• Maryam Daneshpour,
• Soheila Kashanian and
• Kobra Omidfar

Beilstein J. Nanotechnol. 2015, 6, 1677–1689, doi:10.3762/bjnano.6.170

• /Fe3O4. (d) Iron oxide suspensions with (right) and without (left) an external magnetic field. (a) TEM image of Au nanoparticles along with (b) their corresponding particle size distribution. (c) UV–vis absorption spectrum of synthesized Au nanoparticles. (d) Image of a freshly prepared, ruby-red

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

• 10.3762/bjnano.6.167 Abstract The main goal of this work is to study the structural and magnetic properties of iron nanowires and iron nanoparticles, which have been fabricated in almost the same processes. The only difference in the synthesis is an application of an external magnetic field in order to

• nanoparticles, is an application of an external magnetic field in the case of iron nanowires. The remaining part of synthesis has been performed under exactly the same conditions and with the same chemical reagents. Also, both nanomaterials have been stored in sealed vials under air-containing atmosphere. Thus

• structures of both studied nanostructures have been determined by means of transmission electron microscopy (TEM). Recorded images shown in Figure 1 indicate that application or absence of the external magnetic field is a crucial point for the formation of either iron nanowires or iron nanoparticles. Figure

Thermal treatment of magnetite nanoparticles

• Beata Kalska-Szostko,
• Urszula Wykowska,
• Dariusz Satula and
• Per Nordblad

Beilstein J. Nanotechnol. 2015, 6, 1385–1396, doi:10.3762/bjnano.6.143

• , very interesting to study. Taking into account the different nature of the oxides present in the nanosized particles, further investigation of the nanoparticles in an external magnetic field is planned. (A) Mass change of the nanoparticle powders (%) with respect to the temperature variation. (B) Color

Preparation of Ni/Cu composite nanowires

• Hu Wang,
• Xiaoyu Li,
• Ming Li,
• Kenan Xie and
• Li Liao

Beilstein J. Nanotechnol. 2015, 6, 1268–1271, doi:10.3762/bjnano.6.130

• surface of nickel nanowires, named Ni/Cu composite nanowires, was developed for the first time. The synthetic process consisted of two steps. Firstly, pure nickel nanowires were prepared in solution without template by applying a weak external magnetic field. Secondly, the obtained nickel nanowires were

• (a) and Ni/Cu composite nanowires (b). It can be observed from Figure 3a that nickel particles are assembled into a solid linear structure under an external magnetic field, which correspond with our previous research [7][20]. It is obvious that the surface of the Ni/Cu composite nanowires is compact

• self-assembly of nickel particles under an external magnetic field and the reduction of Cu2+ on the surface of prepared nickel nanowires. It is found that an external magnetic field can make nickel particles self-assemble in one dimension, leading to the formation of polycrystalline nickel nanowires

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

• -field cooled/field cooled (ZFC/FC) magnetization measurements and magnetic hysteresis loops recorded in a commercial superconducting quantum interference device (SQUID, Quantum Design) magnetometer. The ZFC/FC curves were collected with an applied external magnetic field of μ0H = 20 mT in a temperature

• range between 10 and 350 K. The measurement geometry was in-plane, i.e., the external magnetic field was applied parallel to the sample surface (as for all magnetic data presented in this paper). Figure 2 shows the TB of the Fex/Cr samples extracted from the ZFC/FC curves. At this point it is reasonable

• interactions) become dominant. Hysteresis loops were recorded at 5 K after field cooling from 350 K, which is above the TN of Cr (311 K [16]), in an external magnetic field of μ0H = 4.5 T. A linear diamagnetic background originating from the Si substrate as well as the Au layers was subtracted. The coercivity

Interaction of electromagnetic radiation in the 20–200 GHz frequency range with arrays of carbon nanotubes with ferromagnetic nanoparticles

• Agylych Atdayev,
• Alexander L. Danilyuk and
• Serghej L. Prischepa

Beilstein J. Nanotechnol. 2015, 6, 1056–1064, doi:10.3762/bjnano.6.106

• material are currently the subject of intensive study. The properties of such materials can be tuned by the external magnetic field, spin-polarized current or electromagnetic radiation. In conventional ferromagnetic materials, the magnetic properties are determined by the domain structure and domain walls

Production, detection, storage and release of spin currents

• Michele Cini

Beilstein J. Nanotechnol. 2015, 6, 736–743, doi:10.3762/bjnano.6.75

• vertices of the polygon represent sites and are acted upon by the spin–orbit interaction and by the external magnetic field B(t). The side length may be taken to be of order of a few angstroms. All sites are connected to the first neighbors by spin-diagonal matrix elements. The Hamiltonian for the left and

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

• sandwich consisting of two permalloy (Py) disks with diameters of 600 and 200 nm separated by a nonmagnetic interlayer are studied. Magnetization reversal of the disk-on-disk nanostructures depends on the distance between centers of the small and big disks and on orientation of an external magnetic field

• different combinations of polarity and chirality [2]. Polarity (up or down out-of-plane component of magnetization in the central core of the vortex state) can be controlled by an external magnetic field aligned perpendicular to a disk plane. This method is complicated to be used for microelectronic

• nanostructures with different distances between its centers, s, which range from 0 (small disk in the center) to 230 nm (small disk at the edge of big disk). We have experimentally studied the effect of the orientation of the disk-on-disk nanostructure relatively to an external magnetic field on the

Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

• Shanka Walia and
• Amitabha Acharya

Beilstein J. Nanotechnol. 2015, 6, 546–558, doi:10.3762/bjnano.6.57

• magnetic field. It was observed that the bifunctional NPs were distributed uniformly in the solution as long as there was an external magnetic field. The detection limit of tripropylamine (TPA) with these sensors was found to be 6.5 nM. Similarly, Santra et al. [28] reported the synthesis of

• superparamagnetic behavior for both iron oxide and the bifunctional nanocomposite with saturation magnetization values of 68.8 and 9.7 emu/g, respectively. To study the application of these NPs in an electrochemiluminescence sensor, these NPs were fabricated on a glassy carbon wafer in the presence of an external

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

• sample at 2 K and 293 K. Inset: Enlargement of the low-field region showing the different coercive fields for the NPs at 2 and 293 K. Attraction of modified nacre with b) no magnetic field and c) external magnetic field (ca. 1 Tesla). Degree of sample swelling plotted as a function of the swelling time