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

Influence of the thickness of an antiferromagnetic IrMn layer on the static and dynamic magnetization of weakly coupled CoFeB/IrMn/CoFeB trilayers

• Deepika Jhajhria,
• Dinesh K. Pandya and
• Sujeet Chaudhary

Beilstein J. Nanotechnol. 2018, 9, 2198–2208, doi:10.3762/bjnano.9.206

• function of the angle θ. The two-fold symmetry for all samples clearly indicates the existence of the uniaxial magnetic anisotropy (UMA). This UMA results from the breakdown of the azimuthal symmetry in the deposited films, which is likely to be caused by the anisotropic stress in the films generated due

• the high anisotropy field [44][45]. The g values of the trilayer films do not vary much with tIrMn and their influence on the properties related to spin–orbit coupling (SOC), such as magnetic anisotropy and damping is not expected to be significant. The effective magnetization is related to the

• in the magnitude and direction of both magnetization and magnetic anisotropy. It could be associated with the magnetic disorder created due to the large interfacial roughness of IrMn at higher tIrMn, which is also supported well by the XRR fitting results. On the other hand, the extrinsic

Synthesis of hafnium nanoparticles and hafnium nanoparticle films by gas condensation and energetic deposition

• Irini Michelakaki,
• Nikos Boukos,
• Dimitrios A. Dragatogiannis,
• Spyros Stathopoulos,
• Costas A. Charitidis and
• Dimitris Tsoukalas

Beilstein J. Nanotechnol. 2018, 9, 1868–1880, doi:10.3762/bjnano.9.179

• demonstrate high catalytic activity during hydrogenation of levulinic acid [17], nickel NPs, which find application as electrochemical sensor [18], and cobalt NPs, which exhibit high magnetic anisotropy [19]. Recently, we have reported that hcp hafnium nanoparticles fabricated by inert-gas condensation, when

Magnetic properties of Fe₃O₄ antidot arrays synthesized by AFIR: atomic layer deposition, focused ion beam and thermal reduction

• Juan L. Palma,
• Alejandro Pereira,
• Raquel Álvaro,
• José Miguel García-Martín and
• Juan Escrig

Beilstein J. Nanotechnol. 2018, 9, 1728–1734, doi:10.3762/bjnano.9.164

• of the holes has to be of the same order of magnitude as the domain wall width. Assuming Bloch-type domain walls, the width W is given by where A is the exchange constant and K is the magnetic anisotropy. Taking common values of A = 15.3 × 10−12 J/m [37] and K = 2.1 × 104 J/m3 [38], W = 84 nm is

Field-controlled ultrafast magnetization dynamics in two-dimensional nanoscale ferromagnetic antidot arrays

• Anulekha De,
• Sucheta Mondal,
• Sourav Sahoo,
• Saswati Barman,
• Yoshichika Otani,
• Rajib Kumar Mitra and
• Anjan Barman

Beilstein J. Nanotechnol. 2018, 9, 1123–1134, doi:10.3762/bjnano.9.104

• strength and orientation of the bias field [6][7][8][19][20][21][22][23][24][25][26]. Intrinsic configurational magnetic anisotropy arising due to the internal field variation can be tuned effectively by varying the antidot lattice symmetry [21][24]. The shape of the antidots is found to control the SW

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

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

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

• 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

• modified Stoner–Wohlfarth model combined with the geometrical approach of the coherent rotation of magnetization [26]. We introduced a bi-axial contribution to completely describe the effective magnetic anisotropy energy (MAE) [27]. For all samples, we have reached a reliable determination of all the

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

• 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

Antitumor magnetic hyperthermia induced by RGD-functionalized Fe₃O₄ nanoparticles, in an experimental model of colorectal liver metastases

• Oihane K. Arriortua,
• Eneko Garaio,
• Borja Herrero de la Parte,
• Maite Insausti,
• Luis Lezama,
• Fernando Plazaola,
• Jose Angel García,
• Jesús M. Aizpurua,
• Maialen Sagartzazu,
• Mireia Irazola,
• Nestor Etxebarria,
• Ignacio García-Alonso,
• Alberto Saiz-López and
• José Javier Echevarria-Uraga

Beilstein J. Nanotechnol. 2016, 7, 1532–1542, doi:10.3762/bjnano.7.147

• . Magnetite-based systems are an interesting alternative due to the relatively high saturation magnetization, magnetic anisotropy, and lack of toxicity, together with the possibility of tailoring the dimensions, parameters which strongly influence the specific adsorption rate (SAR) [15][16][17]. Additionally

• of the blocking temperature is in good accord with the relatively large mean size of the NPs (around 19 nm) taking into account that TB = K·V / 25·kB, where K is the effective magnetic anisotropy constant, V is the mean volume of the NPs, and kB is the Boltzmann constant [42]. Nevertheless, the broad

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

• -prepared ZFO nanoparticles at an applied field of 10 mT are shown in Figure 5. As seen, the magnetic moment continuously increases until a maximum, Tmax, is reached at about 22 K. The fact that this maximum is rather sharp supports the size uniformity of the particles with a similar magnetic anisotropy

• superparamagnetic particle ensembles, where K is the effective uniaxial magnetic anisotropy, V is the particle volume and kB is the Boltzmann’s constant [43]. As shown in Supporting Information File 1, Figure S7, the frequency dependence of the peak temperature does not follow Néel–Brown model, which is supported

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

• , 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

• a consequence of the presence of magnetic anisotropy, the slow relaxation of magnetization has been probed by measuring ac susceptibilities as a function of the temperature at different frequencies as well as a function of frequency at different temperatures. The plots are illustrated in Supporting

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

• 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

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

• 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

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

• Numerical simulations We considered a system with spherical nanoparticles made of uncoated magnetite, with the following characteristics: density ρ = 5180 kg/m3 [3]; saturation magnetization Ms = 4.46·105 A/m [3]; uniaxial magnetic anisotropy with anisotropy constant Keff = 25·103 J/m3 [3]; random

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

• high saturation magnetization (72 emu/g) [38]. But the weakening of magnetic anisotropy shifts the resonance to lower frequencies. The resonance frequency directly depends on saturation magnetization and coercivity [39]. The surface effects become prominent when particle sizes are in the nanometre

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

• magnetocrystalline anisotropy effects and, as a consequence, shape anisotropy will determine the magnetic anisotropy of the wires. The Fe content determined by EELS inside the wires is around 85%, in good agreement with the EDS performed inside the FIB-SEM equipment. According to previous studies, the saturation

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

• antiferromagnetic (AFM) phases a spin exchange coupling occurs and a part of the magnetic moments of the FM phase become pinned. This results in an increased magnetic anisotropy manifesting itself as an exchange bias effect (EB) [3]. The EB appears as a horizontal shift of the magnetization loops, the EB field Heb

• deposited in the AFM Cr matrix unambiguously points out the decisive role of FM/AFM exchange coupling in the enhancement of the magnetic anisotropy. For lower DNN the effect of the particle size on TB gets even less pronounced, since magnetic inter-particle interactions (e.g., strong dipole–dipole

Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

• Oleksandr V. Dobrovolskiy,
• Maksym Kompaniiets,
• Roland Sachser,
• Fabrizio Porrati,
• Christian Gspan,
• Harald Plank and
• Michael Huth

Beilstein J. Nanotechnol. 2015, 6, 1082–1090, doi:10.3762/bjnano.6.109

• the formation of the CoPt L10 phase with strongly increased magnetic anisotropy compared to pure Co. Here, we employ direct writing of Pt and Co layers by FEBID and demonstrate by means of in situ post-processing how to locally tune the coercive field and the remanent magnetization of layered Co/Pt

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

• Lisa Michez,
• Kai Chen,
• Fabien Cheynis,
• Frédéric Leroy,
• Alain Ranguis,
• Haik Jamgotchian,
• Margrit Hanbücken and
• Laurence Masson

Beilstein J. Nanotechnol. 2015, 6, 777–784, doi:10.3762/bjnano.6.80

• -dimensional (2D) and one-dimensional (1D) Co nanostructures has shown that magnetic properties are highly size dependent, due to the low coordination of the atoms of atomic-scale nanostructures [1][18]. For such nanostructures, enhanced magnetic anisotropy energy (MAE) and orbital moment have been evidenced

• as compared to the bulk material. Concerning 1D nanostructures, additional effects, especially with regards to magnetic anisotropy, are expected, related to their anisotropic shape [1][19][20]. Since metallic substrates are known to strongly influence the magnetic properties of the supported

• structure is therefore used to study the magnetic anisotropy in the Co nanolines. The hysteresis loops, obtained from the XMCD signal, were recorded at 4 K for different angles Θ varying from normal incidence (Θ = 0°) to grazing incidence (Θ = 70°) using the measurement geometry presented in Figure 4b. Note

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

• by using OOMMF software [9] with standard parameters for Py: Ms = 860 Gs, exchange stiffness A = 1.38 · 106 erg/cm, damping factor α = 0.05 [11]. The magnetic anisotropy was chosen zero in order not to insert an asymmetry of magnetic properties into the system. Dimension of the simulated disk-on-disk

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

• characteristic for superparamagnetic material [39] with a particle size less than 20 nm. Due to magnetic anisotropy the hysteresis curve at T = 2 K shows ferrimagnetic hysteresis. The saturation magnetization for all analyzed samples is around 26 emu/g at 298 K and 36 emu/g at 2 K which are similar values

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• active component toward metal-organic reactions. For instance, this enhanced catalytic activity in comparison to the single component nanoparticles was demonstrated for Ni@Fe2O3 [45] or Pt@Fe3O4 [46]. Furthermore, the magnetic anisotropy and coercivity of Fe3O4 was significantly increased due to