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

• thin organic semiconductor layer is sandwiched between two ferromagnetic electrodes [24]. A spin-polarized current is injected from one of these electrodes and transported through the semiconductor. Another type also implements spin current, but without charge current, in the structure ferromagnetic

• metal/organic semiconductor/nonmagnetic metal, in which the first interface induces spin pumping [25]. Other devices do not rely on spin manipulation by ferromagnetic layers, but on the intrinsic properties of the organic semiconductor to show, for instance, organic magnetoresistance [26]. These devices

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

• susceptibility measurements (for 7 and 8) and (broken symmetry) density functional theory (DFT) calculations. An S = 2 ground state is demonstrated by temperature-dependent susceptibility and magnetization measurements, achieved by ferromagnetic coupling between the spins of the Ni(II) ions in 7 (J = +22.3 cm−1

• characterized by an S = 2 ground state that is attained by a net ferromagnetic exchange interaction with J values ranging from approximately +15 to +25 cm−1 (H = −2JS1S2) [50]. To gain insight into the magnetic properties of the present complexes, variable-temperature magnetic susceptibility data were measured

• an intramolecular ferromagnetic exchange interaction. This would lead to an St = 2 ground state, in agreement with other carboxylato-bridged compounds supported by L. The decrease in χMT below 20 K can be attributed to zero-field splitting of Ni(II) [51]. The magnetic moment data were analyzed in

Charge transport in organic nanocrystal diodes based on rolled-up robust nanomembrane contacts

• Vineeth Kumar Bandari,
• Lakshmi Varadharajan,
• Longqian Xu,
• Abdur Rehman Jalil,
• Mirunalini Devarajulu,
• Pablo F. Siles,
• Feng Zhu and
• Oliver G. Schmidt

Beilstein J. Nanotechnol. 2017, 8, 1277–1282, doi:10.3762/bjnano.8.129

• . Furthermore, the candidate materials for rolled-up nanomembranes are metals, ferromagnetic layers, oxides, and complex materials, of which the various properties of thin solid films, e.g., work function and magnetic properties, can be utilized to develop novel functional organic devices [30][31]. In our

Atomic structure of Mg-based metallic glass investigated with neutron diffraction, reverse Monte Carlo modeling and electron microscopy

• Rafał Babilas,
• Dariusz Łukowiec and
• Laszlo Temleitner

Beilstein J. Nanotechnol. 2017, 8, 1174–1182, doi:10.3762/bjnano.8.119

• pure and doped ZnO films with thickness from 50 to 200 nm, which contained equiaxial grains of about 20 nm length. Moreover, the ZnO films exhibited ferromagnetic behavior. The structure of the ribbons in the as-cast state was preliminary checked by conventional X-ray diffraction (XRD) in the

Energy-level alignment at interfaces between manganese phthalocyanine and C₆₀

• Daniel Waas,
• Florian Rückerl,
• Martin Knupfer and
• Bernd Büchner

Beilstein J. Nanotechnol. 2017, 8, 927–932, doi:10.3762/bjnano.8.94

• an unusual spin-state of the Mn2+ ion of S = 3/2 and shows a weak ferromagnetic interaction in the bulk [43]. In this respect, thorough studies of MnPc in comparison to other transition-metal phthalocyanines (e.g., CuPc) widens our knowledge and understanding of these systems and beyond. In this

The role of 2D/3D spin-polarization interactions in hybrid copper hydroxide acetate: new insights from first-principles molecular dynamics

• Ziyad Chaker,
• Guido Ori,
• Mauro Boero and
• Carlo Massobrio

Beilstein J. Nanotechnol. 2017, 8, 857–860, doi:10.3762/bjnano.8.86

• detailed analysis of the intralayer spin configurations occurring for each value of the imposed projection along the z-axis for the total spin and of the applied pressure. The transition from an antiferromagnetic to a ferromagnetic state at high pressure (above 3 GPa) goes along with a vanishing difference

• (within each layer) a weak ferromagnetic (F) intralayer (2D) character. The use of pressure is a valuable and practical tool to tune the magnetic behavior of this lamellar hybrid material [4]. In our previous studies, first-principles molecular dynamics (FPMD) approaches combined with density functional

• on each layer. Eventually, the most stable system under pressure features S = 8 as resulting from equal contributions of S1 = 4 and S2 = 4 on each layer. This spin configuration is the best suited to optimize the overall ferromagnetic character of this compound. Conclusion We show that in Cu2(OH

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

• 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

• microscopy; hierarchical nanostructures; magnetic moment; tetramethylazanium hydroxide (TMAH); Introduction The synthesis of ferromagnetic nanomaterials with complex functional architectures has seen rapid development during the past decade [1][2][3]. Cobalt nanostructures form an important class of

• ferromagnetic materials because of distinctive magnetic properties such as an exponential dependence of the magnetization relaxation time on the volume of a particle [4], high susceptibility, many available crystal structures [5] and the uniaxial magnetic axis in hexagonal close-package (hcp) cobalt [6], which

Grazing-incidence optical magnetic recording with super-resolution

• Gunther Scheunert,
• Sidney. R. Cohen,
• René Kullock,
• Ryan McCarron,
• Katya Rechev,
• Ifat Kaplan-Ashiri,
• Ora Bitton,
• Paul Dawson,
• Bert Hecht and
• Dan Oron

Beilstein J. Nanotechnol. 2017, 8, 28–37, doi:10.3762/bjnano.8.4

• be the cause: switching dynamics of nanoscopic ferromagnetic grains in the absence of laser heating, as in PMR media, are typically ~10 ns and heat-assistance is known to speed up the magnetic reversal process significantly [21]. It is a noteworthy observation that, although light is incident under a

From iron coordination compounds to metal oxide nanoparticles

• Mihail Iacob,
• Carmen Racles,
• Codrin Tugui,
• George Stiubianu,
• Adrian Bele,
• Liviu Sacarescu,
• Daniel Timpu and
• Maria Cazacu

Beilstein J. Nanotechnol. 2016, 7, 2074–2087, doi:10.3762/bjnano.7.198

• , magnetite is ferromagnetic when the particle diameter is larger than 15 nm and superparamagnetic when smaller [8]. Zhen et al. demonstrate that cubic nanoparticles have higher saturation magnetization and T2 relaxation than spherical nanoparticles of the same size [9]. Magnetic nanoparticles with flat

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

• Materials Science, Russian Academy of Sciences, Leninsky prospect 49, 117991 Moscow, Russia 10.3762/bjnano.7.185 Abstract The possibility to attain ferromagnetic properties in transparent semiconductor oxides such as ZnO is very promising for future spintronic applications. We demonstrate in this review

• that ferromagnetism is not an intrinsic property of the ZnO crystalline lattice but is that of ZnO/ZnO grain boundaries. If a ZnO polycrystal contains enough grain boundaries, it can transform into the ferromagnetic state even without doping with “magnetic atoms” such as Mn, Co, Fe or Ni. However, such

• multilayer grain boundary segregation. Keywords: ferromagnetism; grain boundaries; zinc(II) oxide (ZnO); Review Introduction In 2000 the seminal work of Tomasz Dietl et al. appeared [1]. In this work it was predicted theoretically that many semiconductor oxides can become ferromagnetic (FM) if one dopes

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

• .7.177 Abstract Near the point of equiatomic composition, both FeRh and FeCo bulk alloys exhibit a CsCl-type (B2) chemically ordered phase that is related to specific magnetic properties, namely a metamagnetic anti-ferromagnetic/ferromagnetic transition near room temperature for FeRh and a huge magnetic

• annealed nanoalloys. Using different experimental measurements, we show how decreasing the size affects the magnetic properties. FeRh nanoparticles keep the ferromagnetic order at low temperature due to surface relaxation affecting the cell parameter. In the case of FeCo clusters, the environment

• 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

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

• of 50 ± 5 nm in diameter and 25 μm in length, i.e., with an aspect ratio of 500. XRD data demonstrate the polycrystalline nature of Ni and Ni–Fe in a face-centered cubic close-packed lattice. Both fabricated materials, Ni and Ni–Fe, have shown ferromagnetic properties. The specific magnetization

• bulk Ni (σ ≈ 58.9 A·m2·kg−1) [44]. For this sample, the cooling behavior is strongly ferromagnetic. The specific magnetization value of Ni-Fe in the alumina template (80 A·m2·kg−1, heating mode, Figure 7) is higher than that of the PA/Ni NWs (Figure 6) and bulk Ni and less with respect to permalloy (Py

• = Fe20Ni80, σ ≈ 100 A·m2·kg−1 [45]). The σ(T) curve measured in the cooling mode indicates significantly smaller σ values, but the cooling behavior for this sample is also ferromagnetic. The decrease of specific magnetization after heating in vacuum (measuring specificity) could be caused by interaction of

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

• ) and anti-parallel (OFF) states of two ferromagnetic domains on either side of a thin insulating barrier. These ferromagnetic domains and the insulating barrier make up the magnetic tunnel junction (MTJ) of the STT-MRAM device. The device is switched between the ON and OFF states by passing a current

• material stack the CoFeB layers are the ferromagnetic domains of the MTJ, MgO is the thin insulating layer, and Ta/CoPd/Ru is the synthetic antiferromagnetic layer. The material stack modeled is from a device reported by Worledge et al. [8]. The thermal stability factor of the free ferromagnetic layer of

• asymmetry is important because thermal assistance requires heating of the free ferromagnetic domain, causing thermal destabilization. But the free domain only experiences significant heating when the device is in positive polarity. Thus care must be taken to ensure the free domain achieves a sufficiently

Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

• Stefan Kolenda,
• Peter Machon,
• Detlef Beckmann and
• Wolfgang Belzig

Beilstein J. Nanotechnol. 2016, 7, 1579–1585, doi:10.3762/bjnano.7.152

• . Keywords: spintronics, superconductor-ferromagnet hybrids, thermoelectricity; Introduction Electrons in classical superconductors are bound in spin-singlet Cooper pairs, whereas ferromagnetic materials prefer parallel spin alignment. In nanoscale hybrid structures made of superconductors and ferromagnets

• , we elucidate the relation of thermoelectric currents to superconducting microrefrigerators by generalizing Onsager relations. Throughout this paper, we will use F, S, I and N to denote ferromagnetic, superconducting, insulating and normal-metal parts of our structures, e.g., FIS for a ferromagnet

• experimental data (see below). Experiment and Results Our samples were fabricated by e-beam lithography and shadow evaporation. The central part is a tunnel junction between ferromagnetic iron and superconducting aluminum, with a thin aluminum oxide layer as tunnel barrier. An additional copper wire is

Influence of synthesis conditions on microstructure and phase transformations of annealed Sr₂FeMoO_6−x nanopowders formed by the citrate–gel method

• Marta Yarmolich,
• Nikolai Kalanda,
• Sergey Demyanov,
• Herman Terryn,
• Jon Ustarroz,
• Maksim Silibin and
• Gennadii Gorokh

Beilstein J. Nanotechnol. 2016, 7, 1202–1207, doi:10.3762/bjnano.7.111

• the antiferromagnetic inclusions in the ferromagnetic matrix to the paramagnetic state. The detected anomalies on the curves of the heat capacity temperature dependences are caused by the transformation temperature of about 426.2, 414.4, and 404.6 K, respectively. The temperature dependences of the

• magnetization [23] also confirm that assumption, which can be associated with the transition of Sr2FeMoO6−x from the ferromagnetic to the paramagnetic state. It is noted that the dependence of the Curie temperature, TC, on the degree of the superstructural ordering has a complicated nonlinear appearance, and

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

• modifications consisted in non-covalent functionalization. Direct in situ generation of superpara- and ferromagnetic species in the presence of these derivatives of oMWCNT were reported. Wu co-precipitated Fe(II) and Fe(III) chlorides with NaOH in oMWCNT dispersion, obtaining a nanocrystalline deposit of Fe3O4

• typical behavior of a superparamagnetic body. Marangon observed a ferromagnetic component for the FC and ZFC magnetization curves which was assigned to the residual nanoparticles left after the catalyst had not sufficiently washed out in the pretreatment procedure [36]. On the other hand, a trivial test

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

• ); AFM probes; high-resolution microscopy; magnetic force microscopy (MFM); magnetic materials; Introduction Conventional MFM probes consist of pyramidal Si or SiN tips with a ferromagnetic thin film coating (generally a CoCr alloy) mounted on a cantilever with resonance frequency and spring constant of

• sensitivity must be found. For this reason, different kinds of commercial MFM probes are available for sale. Specific low-moment or side-coated probes (having lower amounts of ferromagnetic material) can be found in the market. However, best lateral resolution is achieved with super-sharp tips. All these

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

• . [23], the frequency shift Δf induced by a high-aspect ratio, single domain ferromagnetic cylinder placed on a cantilever is given by Equation 3. Combining Equation 3 and Equation 9, the minimal detectable magnetic moment is: From this expression one can conclude that it is favorable to have a small

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

• -workers [22]. Upon deposition of these molecules onto a ferromagnetic surface, a hybridized organometallic supramolecular magnetic layer can be formed. This interface layer exhibits a spin-dependent resistance leading to an interface magnetoresistance (IMR) effect. These findings suggest that phenalenyl

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

• nanowires are crystalline and mainly consist of cobalt as well as a small amount of platinum. Magnetic measurements showed that the resultant cobalt nanowires were ferromagnetic at room temperature. The saturation magnetization (Ms) and the coercivity (Hc) were 112.00 emu/g and 352.87 Oe, respectively

• . 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

• cobalt nanowires obtained in aqueous solution under an external magnetic field of 40 mT. An expanded plot is shown in the insert for field strengths between −6000 Oe and 6000 Oe. The hysteresis loop suggested that the synthesized cobalt nanowires were ferromagnetic at room temperature, which differs from

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

• valve is realized with S = Nb a singlet superconductor, F1 = Cu41Ni59 and F2 = Co ferromagnetic metals, AF = CoOx an antiferromagnetic oxide, and N = nc-Nb a normal conducting (nc) non-magnetic metal, which serves to decouple F1 and F2. The non-collinear alignment of the magnetizations is obtained by

• smaller than 0.3 to 0.4 times the magnetic coherence length, ξF1. Keywords: heterostructures; superconducting spin valve; thin films; triplet superconductivity; Introduction Fulde and Ferrell [1], and Larkin and Ovchinnikov [2] (FFLO) predicted superconductivity on a ferromagnetic background, i.e., in

• interaction with a CoOx film. This shifts the coercive field of the Co film, Hc,Co, to high negative fields with respect to the cooling-field direction, yielding clear separation of the coercive fields of the two ferromagnetic layers [55]. At the small negative coercive field of the Cu41Ni59 film, Hc,CuNi

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

• et al. [40]. There, the coercive field is tuned by the aspect ratio of ferromagnetic nano-bars. They found a monotonous increase with the bar’s aspect ratio due to increasing shape anisotropy. As will be shown in the next section by means of magnetic force microscopy and micromagnetic simulations

• , the remaining ferromagnetic material between two neighbouring holes can (under certain circumstances) be treated as a single domain bar magnet, and a larger antidot diameter increases the aspect ratio of these bars. This suggests that shape anisotropy is an important driver for the augmented coercive

• minimizes its volume, in analogy to the domain wall pinning in a ferromagnetic nanowire containing a notch [43]. In turn, this pinning becomes more effective the more energy is saved by incorporating the non-magnetic defect into the domain wall, i.e., it scales with the domain wall energy. In this way, the

Microwave solvothermal synthesis and characterization of manganese-doped ZnO nanoparticles

• Jacek Wojnarowicz,
• Roman Mukhovskyi,
• Elzbieta Pietrzykowska,
• Sylwia Kusnieruk,
• Jan Mizeracki and
• Witold Lojkowski

Beilstein J. Nanotechnol. 2016, 7, 721–732, doi:10.3762/bjnano.7.64

• + [22]. Numerous scholars have described obtaining Mn2+-doped zinc oxide, which displays ferromagnetic properties at room temperature, in their papers [23][24][25][26]. However, there are many contradicting or even controversial publications on this topic [27][28][29][30]. Depending on the method of

• obtaining, Zn1−xMnxO may display either ferromagnetic [31] or paramagnetic properties [32]. Various pieces of literature reporting magnetic properties of Zn1−xMnxO NPs result from the impact of the synthesis method on: the heterogeneous distribution of Mn2+ ions in the ZnO crystalline lattice (e.g

• with MnxOy such as ZnMnO3 and ZnMn2O4 were precipitated in the material. The obtained Zn1−xMnxO materials were characterised by either ferromagnetic or paramagnetic properties depending on the presence of foreign phases [33][36][38][39]. This results from different magnetic properties of MnxOy and

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

• compounds containing mainly high-spin Mn(III). In such compounds, the SMM behavior was due to a combination of the Jahn–Teller distortion of the Mn(III), the ferromagnetic alignment of the Mn(IV), and overall antiferromagnetic exchange between the Mn(III) and Mn(IV) leading to a S = 10 ground state [9]. To

• temperature range of 0–7 T and 2–5 K, respectively. We firstly explored the magnetic conduct of the isotropic gadolinium molecule, 1, where some insight whether any interaction (i.e. ferromagnetic or antiferromagnetic) operates within the complex. The room temperature χMT value (where χM is the molar magnetic

• -rate dependent and is due to a direct relaxation process between the ferromagnetic and antiferromagnetic spin states. The loops also show a small hysteresis at μ0H = 0, which comes from the fact that some of the molecules did not tunnel to the antiferromagnetic ground state, but remain in the

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

• and sedimentation increases considerably with the transition from small nanoparticles to stable ferromagnetic single domain [4]. This leads to clogging of blood vessels. The displacement of the domain wall causes the reversal of the magnetization direction in multi-domain nanoparticles. In a single

• calculation and experimental results [21]. This calculation shows the dependence of the relaxation time on the magnetic damping constant α. For the case of most ferromagnetic and ferrimagnetic nanoparticle systems, the magnetic damping constant α exhibits low values (α << 1) [22]. In this section, we adapt