The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

• Hajar Jalili,
• Bagher Aslibeiki,
• Ali Ghotbi Varzaneh and
• Volodymyr A. Chernenko

Beilstein J. Nanotechnol. 2019, 10, 1348–1359, doi:10.3762/bjnano.10.133

• collective magnetic behavior. Studies show that the magnetic properties are strongly affected by the magnetic anisotropy of NPs and by interparticle interactions that are the result of the collective magnetic behavior of NPs. Here we study these effects in more detail. For this purpose, we prepared CoxFe3

• −xO4 NPs, with x = 0–1 in steps of 0.2, from soft magnetic (Fe3O4) to hard magnetic (CoFe2O4) ferrite, with a significant variation of the magnetic anisotropy. The phase purity and the formation of crystalline NPs with a spinel structure were confirmed through Rietveld refinement. The effect of Co

• observed that the heat efficiency of soft Fe3O4 is about 4 times larger than that of hard CoFe2O4 ferrite, which was attributed to the high coercive field of samples compared with the external field amplitude. Keywords: anisotropy; cobalt; ferrite; Henkel plots; hyperthermia therapy; nanoparticles

On the relaxation time of interacting superparamagnetic nanoparticles and implications for magnetic fluid hyperthermia

• Andrei Kuncser,
• Nicusor Iacob and
• Victor E. Kuncser

Beilstein J. Nanotechnol. 2019, 10, 1280–1289, doi:10.3762/bjnano.10.127

• performed on ferrofluids of different volume fractions. The theoretical support for the specific evolution of the relaxation time constant and the anisotropy energy barrier versus the interparticle interactions in a perturbation approach of the simple Néel expression for the relaxation time is provided via

• only to increase the anisotropy energy barrier per nanoparticle but also to decrease the specific time constant in the simplest Néel–Brown expression of the relaxation time, which is usually considered only as a material dependent parameter. In this context, the threefold aim of this paper is: (i) to

• measurements and (iii) to provide theoretical support for the specific evolution of the relaxation time constant and the anisotropy energy barrier in the Néel expression as function of interparticle interaction through a suitable exploitation of static and time-dependent micromagnetic simulations. Results and

Tailoring the magnetic properties of cobalt ferrite nanoparticles using the polyol process

• Malek Bibani,
• Romain Breitwieser,
• Alex Aubert,
• Vincent Loyau,
• Silvana Mercone,
• Souad Ammar and
• Fayna Mammeri

Beilstein J. Nanotechnol. 2019, 10, 1166–1176, doi:10.3762/bjnano.10.116

• while the sub-stoichiometric NPs (particularly for x ≈ 0.7) are expected to be less magnetostrictive but to present a higher magnetocrystalline anisotropy constant, as previously observed in bulk cobalt ferrites. To control the size of the NPs, in order to overcome the superparamagnetic limit, as well

• piezoelectric polymers. Keywords: cobalt ferrite; magnetocrystalline anisotropy; magnetostriction; nanoparticle; non-stoichiometry; polyol process; Introduction Recently, extrinsically (or artificially) magnetoelectric (ME) multiferroic (MF) materials have been seriously investigated for many applications in

• anisotropy of polycrystalline CoxFe3−xO4. The anisotropy was found to be the highest for x = 0.7 and 0.8 and the lowest for x = 0.2. However, the most interesting magnetostriction effects were found at the composition of x = 1. Therefore, the stoichiometry appears to be a key-parameter to tailor the

Nanoscale optical and structural characterisation of silk

• Meguya Ryu,
• Reo Honda,
• Adrian Cernescu,
• Arturas Vailionis,
• Armandas Balčytis,
• Jitraporn Vongsvivut,
• Jing-Liang Li,
• Denver P. Linklater,
• Elena P. Ivanova,
• Vygantas Mizeikis,
• Mark J. Tobin,
• Junko Morikawa and
• Saulius Juodkazis

Beilstein J. Nanotechnol. 2019, 10, 922–929, doi:10.3762/bjnano.10.93

• , Melbourne, Australia 10.3762/bjnano.10.93 Abstract The nanoscale composition of silk defining its unique properties via a hierarchial structural anisotropy needs to be analysed at the highest spatial resolution of tens of nanometers corresponding to the size of fibrils made of β-sheets, which are the

• were carried out for comparison at IR wavelengths of 2–10 μm using synchrotron radiation. A reliable distinction of transmission changes by only 1–2% as the anisotropy of amide bands was obtained from nanometer-thin slices of silk. Keywords: absorbance; anisotropy; retardance; silk; Introduction

• properties of a material are interrelated. By using a wide spectrum of electromagnetic waves from visible light to terahertz radiation, it is possible to gain insights into complex hierarchical structures of composite materials. For materials with strong structural anisotropy, defined by the molecular

Magnetic field-assisted assembly of iron oxide mesocrystals: a matter of nanoparticle shape and magnetic anisotropy

• Julian J. Brunner,
• Marina Krumova,
• Helmut Cölfen and
• Elena V. Sturm (née Rosseeva)

Beilstein J. Nanotechnol. 2019, 10, 894–900, doi:10.3762/bjnano.10.90

• orientation of some nanoparticles within the superlattice with <112>magnetite perpendicular to the substrate might be caused by the simultaneous competition of two types of anisotropic interactions between nanoparticles during the assembly process [24]. On one side the particle shape anisotropy promotes face

• -to-face alignment (i.e., interaction of the particle {110} faces with other particle faces within the layer) and on the other side magnetic anisotropy of magnetite nanoparticles induces the alignment of the <111>magnetite easy axis parallel to the direction of the external magnetic field

Co-doped MnFe₂O₄ nanoparticles: magnetic anisotropy and interparticle interactions

• Bagher Aslibeiki,
• Parviz Kameli,
• Hadi Salamati,
• Giorgio Concas,
• Maria Salvador Fernandez,
• Alessandro Talone,
• Giuseppe Muscas and
• Davide Peddis

Beilstein J. Nanotechnol. 2019, 10, 856–865, doi:10.3762/bjnano.10.86

• , the effect of the chemical composition, i.e., the amount of Co doping, produces marked differences on the magnetic properties, especially on the magnetic anisotropy, with evident large changes in the coercive field. Moreover, Co substitution has a profound effect on the interparticle interactions, too

• . A dipolar-based interaction regime is detected for all samples; in addition, the intensity of the interactions shows a possible relation with the single particle anisotropy. Finally, the sample with the strongest interaction regime shows a superspin glass state confirmed by memory effect dynamics

• , hence showing a final net magnetization (ferrimagnetism) which depends directly on the specific population of Td and Oh sites. Furthermore, the magnetic anisotropy of the system is related to the specific cationic population and distribution in the different interstitial sites [19]. In the present paper

Ultrasonication-assisted synthesis of CsPbBr₃ and Cs₄PbBr₆ perovskite nanocrystals and their reversible transformation

• Longshi Rao,
• Xinrui Ding,
• Xuewei Du,
• Guanwei Liang,
• Yong Tang,
• Kairui Tang and
• Jin Z. Zhang

Beilstein J. Nanotechnol. 2019, 10, 666–676, doi:10.3762/bjnano.10.66

• images (Figure 4c–h) clearly confirm that the morphology of these PNCs can be tuned easily by changing the amount of OAm in the precursor solution, while keeping the amount of OA unchanged. We attribute this morphology change to the crystal anisotropy induced by the growth kinetics. The capping ligands

Coexisting spin and Rabi oscillations at intermediate time regimes in electron transport through a photon cavity

• Vidar Gudmundsson,
• Hallmann Gestsson,
• Nzar Rauf Abdullah,
• Chi-Shung Tang,
• Andrei Manolescu and
• Valeriu Moldoveanu

Beilstein J. Nanotechnol. 2019, 10, 606–616, doi:10.3762/bjnano.10.61

• , but only in this regime dominated by strong nonequilibrium processes. In the earlier calculations the central system was a short quantum wire with parallel quantum dots of the same shape. The anisotropy of the system makes the first excitation of the even parity one-electron ground state to be an odd

Mechanical and thermodynamic properties of Aβ₄₂, Aβ₄₀, and α-synuclein fibrils: a coarse-grained method to complement experimental studies

• Adolfo B. Poma,
• Horacio V. Guzman,
• Mai Suan Li and
• Panagiotis E. Theodorakis

Beilstein J. Nanotechnol. 2019, 10, 500–513, doi:10.3762/bjnano.10.51

• molecular understanding. Our approach allows a comparison of diverse elastic properties based on different deformations , i.e., tensile (YL), shear (S), and indentation (YT) deformation. From our analysis, we find a significant elastic anisotropy between axial and transverse directions (i.e., YT > YL) for

• contact area, which will be the arc region that forms in contact with the sphere. In considering other shapes for the cantilever tip, such as conical or flat punch, the impact of the anisotropy is expected to be much higher [16]. Nonetheless, to our knowledge the exact shape of the cantilever tip cannot

• aggregation rate depends on the mechanical stability of the fibrils [27] our study could provide also hints for the self-assembly of β-amyloid and α-synuclein chains. Our results also indicate an elastic anisotropy namely, YT > YL, for all systems. In the case of α-syn fibrils this difference between YT and

Geometrical optimisation of core–shell nanowire arrays for enhanced absorption in thin crystalline silicon heterojunction solar cells

• Robin Vismara,
• Olindo Isabella,
• Andrea Ingenito,
• Fai Tong Si and
• Miro Zeman

Beilstein J. Nanotechnol. 2019, 10, 322–331, doi:10.3762/bjnano.10.31

• bombarding the surface of the sample. Such effect occurs with higher speed on the horizontal than on the vertical plane, due to the larger angle of incidence of ions hitting the vertical side walls, which leads to a strong anisotropy of the Si etching rate. The process is made mask-less by the precipitation

Heating ability of magnetic nanoparticles with cubic and combined anisotropy

• Nikolai A. Usov,
• Mikhail S. Nesmeyanov,
• Elizaveta M. Gubanova and
• Natalia B. Epshtein

Beilstein J. Nanotechnol. 2019, 10, 305–314, doi:10.3762/bjnano.10.29

• , Moscow, Russia National Research Nuclear University “MEPhI”, 115409, Moscow, Russia 10.3762/bjnano.10.29 Abstract The low frequency hysteresis loops and specific absorption rate (SAR) of assemblies of magnetite nanoparticles with cubic anisotropy are calculated in the diameter range of D = 20–60 nm

• anisotropy. A substantial dependence of the SAR on the nanoparticle diameter is obtained for all cases investigated. Due to the influence of the magneto–dipole interaction, the SAR of fractal clusters of nanoparticles decreases considerably in comparison with that for weakly interacting nanoparticles

• magnetic anisotropy have mostly been studied. Meanwhile, perfect iron oxide nanoparticles of spherical shape should have cubic-type magnetic anisotropy [5]. However, to describe the existing experimental data properly one has also to take into account the possible perturbation of the nanoparticle shape. A

Relation between thickness, crystallite size and magnetoresistance of nanostructured La_1−xSr_xMn_yO_3±δ films for magnetic field sensors

• Rasuole Lukose,
• Valentina Plausinaitiene,
• Milita Vagner,
• Nerija Zurauskiene,
• Skirmantas Kersulis,
• Virgaudas Kubilius,
• Karolis Motiejuitis,
• Birute Knasiene,
• Voitech Stankevic,
• Zita Saltyte,
• Martynas Skapas,
• Algirdas Selskis and
• Evaldas Naujalis

Beilstein J. Nanotechnol. 2019, 10, 256–261, doi:10.3762/bjnano.10.24

• additional supply source of precursor solution in an exponentially decreasing manner, exhibit the highest magnetoresistance and the lowest magnetoresistance anisotropy. The possibility to use these films for the development of magnetic field sensors operating at room temperature is discussed. Keywords

• practical applications due to low sensitivity and large magnetic anisotropy [15][16]. For this reason, the investigation and control of the magnetoresistive properties of manganite materials on the nanometer scale is of great importance. It was shown that the change of nanostructure by variation of

• range [1]. In this study, we present the possibility to tune and to select the necessary properties of nanostructured LSMO films by changing the film thickness and microstructure in order to obtain higher sensitivity and lower anisotropy, important for magnetic field sensing. Results and Discussion Two

Interaction of Te and Se interlayers with Ag or Au nanofilms in sandwich structures

• Arkadiusz Ciesielski,
• Lukasz Skowronski,
• Marek Trzcinski,
• Ewa Górecka,
• Wojciech Pacuski and
• Tomasz Szoplik

Beilstein J. Nanotechnol. 2019, 10, 238–246, doi:10.3762/bjnano.10.22

• ], enhanced abrasive properties of metal films [9] as well as effects like charge transport anisotropy [10] and giant magneto-optical Kerr response [11]. We have recently shown that depositing silver with an ultrathin germanium interlayer alters the density profile of the silver film [12]. Among the most

Threshold voltage decrease in a thermotropic nematic liquid crystal doped with graphene oxide flakes

• Mateusz Mrukiewicz,
• Krystian Kowiorski,
• Paweł Perkowski,
• Rafał Mazur and
• Małgorzata Djas

Beilstein J. Nanotechnol. 2019, 10, 71–78, doi:10.3762/bjnano.10.7

• , electric anisotropy, splay elastic constant, switch-on time, and switch-off time. The shape and dimensions of the GO flakes were studied using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The influence of the GO concentration on the physical properties and switching process in the

• the tilt angle θ is small. When the voltage is above Uth, we start to observe the increase of θ [4]. The complete reorientation of the director n, θ = 90°, occurs at higher voltages U > Uth. The reorientation is caused by the anisotropy of the electric permittivity where ε|| and is the electric

• permittivity measured along the directions parallel and perpendicular to n, respectively. In the case of positive electric anisotropy (Δε > 0), the director is forced to align along the electric field. One of the most efficient methods to reduce the threshold voltage in nematic liquid crystals for high electro

A comparison of tarsal morphology and traction force in the two burying beetles Nicrophorus nepalensis and Nicrophorus vespilloides (Coleoptera, Silphidae)

• Liesa Schnee,
• Benjamin Sampalla,
• Josef K. Müller and
• Oliver Betz

Beilstein J. Nanotechnol. 2019, 10, 47–61, doi:10.3762/bjnano.10.5

• ]. For theoretical access to the problem of frictional anisotropy considering factors such as the slope of the surface structures, the rigidity of the joints, and sliding speed, the reader is referred to [44]. Our results are in full accordance with previous measurements of the frictional directionality

Colloidal chemistry with patchy silica nanoparticles

• Pierre-Etienne Rouet,
• Cyril Chomette,
• Laurent Adumeau,
• Etienne Duguet and
• Serge Ravaine

Beilstein J. Nanotechnol. 2018, 9, 2989–2998, doi:10.3762/bjnano.9.278

• molecular systems, the so-called “colloidal molecules” (CMs) [1]. Tremendous efforts have been devoted to the synthesis of particles with directional interactions to replicate bond schemes of molecular systems [2][3][4][5]. One efficient approach is to engineer particles with chemical anisotropy, that is

Size limits of magnetic-domain engineering in continuous in-plane exchange-bias prototype films

• Alexander Gaul,
• Daniel Emmrich,
• Timo Ueltzhöffer,
• Henning Huckfeldt,
• Hatice Doğanay,
• Johanna Hackl,
• Muhammad Imtiaz Khan,
• Daniel M. Gottlob,
• Gregor Hartmann,
• André Beyer,
• Dennis Holzinger,
• Slavomír Nemšák,
• Claus M. Schneider,
• Armin Gölzhäuser,
• Günter Reiss and
• Arno Ehresmann

Beilstein J. Nanotechnol. 2018, 9, 2968–2979, doi:10.3762/bjnano.9.276

• the domain wall width has been investigated as a function of the angle between unidirectional anisotropy and domain wall. By shrinking the domain size of periodic domain stripes, we analyzed the influence of domain wall overlap on the domain stability. Finally, by changing the geometry of artificial

• engineering in an in-plane exchange-bias thin film as a prototypical system. For two-dimensional domains the limit depends on the domain geometry. The relative orientation between domain wall and anisotropy axes is a crucial parameter and therefore influences the achievable minimum domain size dramatically

• ) width, varying with material-specific magnetic parameters, but could not be tested yet. For exchange-bias material systems with in-plane anisotropy, typical DW widths are of the order of several hundreds of nanometers [16] to some micrometers [31]. A patterning method with lateral resolution

The effect of flexible joint-like elements on the adhesive performance of nature-inspired bent mushroom-like fibers

• Elliot Geikowsky,
• Serdar Gorumlu and
• Burak Aksak

Beilstein J. Nanotechnol. 2018, 9, 2893–2905, doi:10.3762/bjnano.9.268

• performance both theoretically and experimentally [13][14][15][16][17][18][19][20][21][22]. Murphy et al. [16] obtained a similar anisotropy ratio in shear to the gecko setae and observed adhesive engagement only when the fibers were moved in the same direction as the tilt angle. They observed that the angle

• aspect of natural curved/tilted fibers is the directional dependence of adhesion and shear. Similar anisotropy can be observed for the samples tested in this work as well (see Figure 6). All the samples exhibit higher shear forces in the gripping than in the releasing direction, the discrepancy being

• magnitude of the response in shear of soft joint fibers suggests that shear force in the gripping direction is approximately twice as high in the releasing direction, providing an anisotropy ratio of 2:1 at the highest applied preload. This ratio is marginally higher for very soft joint fibers. The highest

Magnetic and luminescent coordination networks based on imidazolium salts and lanthanides for sensitive ratiometric thermometry

• Pierre Farger,
• Cédric Leuvrey,
• Mathieu Gallart,
• Pierre Gilliot,
• Guillaume Rogez,
• João Rocha,
• Duarte Ananias,
• Pierre Rabu and
• Emilie Delahaye

Beilstein J. Nanotechnol. 2018, 9, 2775–2787, doi:10.3762/bjnano.9.259

• networks, the luminescent properties can be used to synthesize temperature probes with possible applications in the aerospace area, safety and health [17][18]. Beside luminescent properties, lanthanide ions exhibit large magnetic moment and strong magnetic anisotropy, which might have potential

Oriented zinc oxide nanorods: A novel saturable absorber for lasers in the near-infrared

• Pavel Loiko,
• Tanujjal Bora,
• Josep Maria Serres,
• Haohai Yu,
• Magdalena Aguiló,
• Francesc Díaz,
• Uwe Griebner,
• Valentin Petrov,
• Xavier Mateos and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2018, 9, 2730–2740, doi:10.3762/bjnano.9.255

• a fiber-coupled laser diode (an InGaAs one, emitting at ≈0.978 µm, for the Yb laser, and an AlGaAs one, emitting at ≈0.802 µm, for the Tm laser). The polarization of the laser emission was linear, E || Nm, naturally selected by the anisotropy of the gain. More details about the laser set-up can be

Size-selected Fe₃O₄–Au hybrid nanoparticles for improved magnetism-based theranostics

• Maria V. Efremova,
• Yulia A. Nalench,
• Eirini Myrovali,
• Anastasiia S. Garanina,
• Ivan S. Grebennikov,
• Polina K. Gifer,
• Maxim A. Abakumov,
• Marina Spasova,
• Makis Angelakeris,
• Alexander G. Savchenko,
• Michael Farle,
• Natalia L. Klyachko,
• Alexander G. Majouga and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2018, 9, 2684–2699, doi:10.3762/bjnano.9.251

• -crystalline anisotropy and the saturation magnetization MS as well as on the shape and morphology [37][38][39]. We thus expect that except for sample MNP-44 all magnetite hybrid samples are single domain. The MS (Table 3) is measured at large fields by extrapolation of a linear fit to the ordinate. The MS

• (Table 2). The temperature dependence of the coercive field HC(T) allows us to estimate the effective magnetic anisotropy energy density Keff (Table 3) by using Sharrock’s equation for single domain, randomly oriented, non-interacting NPs [47][48][49]: Random orientation and single domain properties are

• Keff values while the uncertainty intervals have been estimated based on the volume distributions. We obtain 11 ± 7 kJ·m−3 and 10 ± 6 kJ·m−3 for MNP-15 and MNP-25, respectively. These values are in reasonable agreement with the first order anisotropy constant of bulk Fe3O4 K1 = 13 kJ·m−3 [37]. For MNP

Characterization of the microscopic tribological properties of sandfish (Scincus scincus) scales by atomic force microscopy

• Weibin Wu,
• Christian Lutz,
• Simon Mersch,
• Richard Thelen,
• Christian Greiner,
• Guillaume Gomard and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2018, 9, 2618–2627, doi:10.3762/bjnano.9.243

• corresponding averaged friction. In this way, we average between forward and backward friction and neglect the anisotropy of friction due to the comb-like structure [24]. Three different positons on each sample were recorded and the averaged frictional force (data points in Figure 6) and the corresponding

Friction reduction through biologically inspired scale-like laser surface textures

• Johannes Schneider,
• Vergil Djamiykov and
• Christian Greiner

Beilstein J. Nanotechnol. 2018, 9, 2561–2572, doi:10.3762/bjnano.9.238

• convincingly demonstrated frictional anisotropy and a maximum friction reduction of about 50% with biologically inspired surfaces [22]. These investigations relied on a two-step moulding technique for manufacturing scale-like structures and therefore focused on the frictional properties of polymeric samples

• , Supporting Information File 1 for an optical micrograph of a PEEK disc after a dry sliding experiment. As described above, only very limited wear was observed, even though not specifically quantified. When comparing with the literature, it becomes apparent that frictional anisotropy of the laser-generated

• scale-like surface textures needs to be tested in the future. Such effects were reported for a variety of biological systems [55][56] and polymeric [21][22] as well as metallic [24] surface morphologies inspired by snake skin. Modelling efforts revealed that anisotropy is a function of the counter

High-temperature magnetism and microstructure of a semiconducting ferromagnetic (GaSb)_1−x(MnSb)_x alloy

• Leonid N. Oveshnikov,
• Elena I. Nekhaeva,
• Alexey V. Kochura,
• Alexander B. Davydov,
• Mikhail A. Shakhov,
• Sergey F. Marenkin,
• Oleg A. Novodvorskii,
• Alexander P. Kuzmenko,
• Alexander L. Vasiliev,
• Boris A. Aronzon and
• Erkki Lahderanta

Beilstein J. Nanotechnol. 2018, 9, 2457–2465, doi:10.3762/bjnano.9.230

• in Table 1 and the parameters obtained from the Rxy(H) curves is related to a substantial magnetic anisotropy of the samples under study (see Figure 1). The observation of the anomalous Hall effect (AHE) clearly suggests that delocalized holes interact with the magnetic subsystem, i.e., that there

Evidence of friction reduction in laterally graded materials

• Roberto Guarino,
• Gianluca Costagliola,
• Federico Bosia and
• Nicola Maria Pugno

Beilstein J. Nanotechnol. 2018, 9, 2443–2456, doi:10.3762/bjnano.9.229

• produces a nonlinear reduction of static friction with the grading. A quasi-linear decrease can be obtained in the case of a triangular grading, which is symmetric with respect to the two edges, so that the anisotropy of the vertical stress distribution is less influential. In particular, this outcome can