Specific absorption rate of randomly oriented magnetic nanoparticles in a static magnetic field

• Ruslan A. Rytov and
• Nikolai A. Usov

Beilstein J. Nanotechnol. 2023, 14, 485–493, doi:10.3762/bjnano.14.39

• in a sufficiently strong dc field is absent, since magnetization reversal of nanoparticles is impossible. Hdc is perpendicular to Hac Let us now consider the case of perpendicular orientation of the external dc and the ac magnetic fields. The dc magnetic field changes in this case in the range Hdc

• at φ = π (see Figure 4c). As a result, the height of the energy barrier between the potential wells decreases significantly. This leads to an increase in the probability of magnetization reversal of nanoparticles of large diameters, D = 30–50 nm. At Hdc = 200 Oe, this gives an almost rectangular

• nanoparticles, D > 30 nm, a significant decrease in SAR can occur near the FFP, where the dc field is low, since the magnetization reversal of large particles in this region is prohibited. (a) Dependence of the SAR of randomly oriented assemblies of nanoparticles of various diameters distributed in a solid

Nonlinear features of the superconductor–ferromagnet–superconductor φ₀ Josephson junction in the ferromagnetic resonance region

• Aliasghar Janalizadeh,
• Ilhom R. Rahmonov,
• Sara A. Abdelmoneim,
• Yury M. Shukrinov and
• Mohammad R. Kolahchi

Beilstein J. Nanotechnol. 2022, 13, 1155–1166, doi:10.3762/bjnano.13.97

• –voltage (I–V) characteristics by magnetic dynamics in the ferromagnet, in particular, to create a DC component in the superconducting current [6][7][8]. A remarkable manifestation of this coupling is the possibility to stimulate a magnetization reversal in the ferromagnetic layer by applying a current

Controllable two- and three-state magnetization switching in single-layer epitaxial Pd_1−xFe_x films and an epitaxial Pd_0.92Fe_0.08/Ag/Pd_0.96Fe_0.04 heterostructure

• Igor V. Yanilkin,
• Amir I. Gumarov,
• Gulnaz F. Gizzatullina,
• Roman V. Yusupov and
• Lenar R. Tagirov

Beilstein J. Nanotechnol. 2022, 13, 334–343, doi:10.3762/bjnano.13.28

• the film. In a wide range of the appled field directions, the magnetization reversal proceeds in two steps via the intermediate easy axis. An epitaxial heterostructure of two magnetically separated ferromagnetic layers, Pd0.92Fe0.08/Ag/Pd0.96Fe0.04, was synthesized and studied with dc magnetometry

• . Its magnetic configuration diagram has been constructed and the conditions have been determined for a controllable switching between stable parallel, orthogonal, and antiparallel arrangements of magnetic moments of the layers. Keywords: anisotropic magnetoresistance; magnetization reversal; Pd–Fe

• magnetic moment by 90° in epitaxial Pd1−xFex films has not been yet explored. In [18][19], based on magnetometry data, it was assumed that magnetization reversal occurs as a result of the coherent rotation of the magnetic moment by 180°; and in the study of the Pd0.96Fe0.04/VN/Pd0.92Fe0.08 structure [23

Heating ability of elongated magnetic nanoparticles

• Elizaveta M. Gubanova,
• Nikolai A. Usov and
• Vladimir A. Oleinikov

Beilstein J. Nanotechnol. 2021, 12, 1404–1412, doi:10.3762/bjnano.12.104

• superparamagnetic nanoparticle substantially depends on the value of the reduced energy barrier [18]. At a large value of the reduced energy barrier, σ ≫ 1, the probability of a nanoparticle magnetization reversal in an ac magnetic field of moderate amplitude, H0 ≪ Hk, where Hk = 2Kef/Ms is the particle anisotropy

• effective anisotropy constant Kef the magnetization reversal process is only possible for nanoparticles with a reduced volume. This fact explains the shift of the domain of optimal particle diameters to smaller sizes with an increase in the aspect ratio a/b. Simultaneously, a narrowing of the window of

A review of defect engineering, ion implantation, and nanofabrication using the helium ion microscope

• Frances I. Allen

Beilstein J. Nanotechnol. 2021, 12, 633–664, doi:10.3762/bjnano.12.52

• comprising an arrangement of discs of 100 nm diameter with a pitch of 200 nm were irradiated, demonstrating the capability of the focused helium ion beam method to achieve magnetic property engineering in the form of a nanoscale periodic array. In follow-up work, consistent magnetization reversal for all

Unipolar magnetic field pulses as an advantageous tool for ultrafast operations in superconducting Josephson “atoms”

• Daria V. Popolitova,
• Nikolay V. Klenov,
• Igor I. Soloviev,
• Sergey V. Bakurskiy and
• Olga V. Tikhonova

Beilstein J. Nanotechnol. 2019, 10, 1548–1558, doi:10.3762/bjnano.10.152

• Communications and Informatics (MTUCI), 111024 Moscow, Russia Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia 10.3762/bjnano.10.152 Abstract A theoretical approach to the consistent full quantum description of the ultrafast population transfer and magnetization

• reversal in superconducting meta-atoms induced by picosecond unipolar pulses of a magnetic field is developed. A promising scheme based on the regime of stimulated Raman Λ-type transitions between qubit states via upper-lying levels is suggested in order to provide ultrafast quantum operations on the

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

• provided additional information about the magnetization reversal of each sample. The derivative of MDCD with respect to the reversal field, χirr = dMDCD/dµ0H, represents the irreversible component of the susceptibility. This quantity is generally defined as the switching field distribution (SFD) [47][48

• anisotropy, it exhibits the strongest effective interaction regime, actually showing a super-spin-glass behavior. Tuning the anisotropy is one way to control the overall magnitude of the interactions, opening new interesting perspectives for controlling the magnetization reversal of concentrated NP systems

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

• diameter. For small particle diameters, the effective energy barrier is too small at room temperature. Therefore, the alternating magnetic field has little influence on the assembly behavior. For large particle diameters the barriers are too large, so that the magnetization reversal of the particle is

• impossible or less probable under an alternating magnetic field of moderate amplitude. However, the probability for particle magnetization reversal increases with the increase in magnetic field amplitude [15]. As Figure 3b shows, in the case H0 = 100 Oe, the probability of the magnetization reversal is

• the hysteresis loop in Figure 4 decreases as a function of average particle elongation because the shape anisotropy energy increases the effective energy barrier. Thus the probability of the magnetization reversal at a fixed value of the magnetic field amplitude decreases. This effect deserves special

Magnetism and magnetoresistance of single Ni–Cu alloy nanowires

• Andreea Costas,
• Camelia Florica,
• Elena Matei,
• Maria Eugenia Toimil-Molares,
• Ionel Stavarache,
• Andrei Kuncser,
• Victor Kuncser and
• Ionut Enculescu

Beilstein J. Nanotechnol. 2018, 9, 2345–2355, doi:10.3762/bjnano.9.219

• single magnetic nanowires in the peculiar cases of Stoner–Wohlfarth-like magnetization reversal mechanisms. The magnetic parameters of single Ni–Cu nanowires of different Ni content have been estimated and discussed by the interpretation of the as derived magnetic hysteresis loops via micromagnetic

• also related to an exchange length parameter, λex = π√(A/K), where A is the exchange stiffness and K is the anisotropy constant, respectively. Even for single-component metallic nanowires (e.g., Ni) of high aspect ratio, different magnetization reversal mechanisms might be in work (from the simplest

• specific to GMR systems. To date, less interest has been shown for the magnetoresistive properties of overall alloy nanowires, where magnetic parameters influencing the magnetization reversal (e.g., A, K or the local value of the spontaneous magnetization) and hence the scattering of the conduction

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

• between two FM layers through an AF layer. Motivated by this, we chose a rather uncommon CoFeB(10 nm)/IrMn(tIrMn)/CoFeB(10 nm) trilayer system to investigate the interlayer exchange coupling, spin transport, magnetic damping and magnetization reversal by carrying out ferromagnetic resonance (FMR) and

• reversal of the two CoFeB layers is indeed magnetically coupled in the trilayer system. For tIrMn ≥ 7 nm, the magnetization reversal of the two CoFeB layers gets decoupled as confirmed by the appearance of a kink in the M–H loop. Neither exchange bias nor loop broadening are observed at RT, which indicates

• thickness range. For tIrMn ≥ 4 nm, the magnetization reversal is symmetric and more rounded, and a weak and positive exchange bias (PEB) also appears. The strength of PEB increases with further increasing tIrMn as shown in Figure 8d–f. A similar positive exchange bias has been reported earlier in IrMn/CoFeB

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

• they act as pinning centers for the domain wall motion during magnetization reversal. If a is the lattice constant (nearest neighbor center-to-center distance) and d is the hole diameter, the defect volume density (DVD), which is the ratio of the surface covered by holes to the total surface, is given

• pinning zones during the magnetization reversal process. The remanence exhibits the opposite behavior with values close to 0.8. Conclusion In conclusion, we have demonstrated the technical feasibility of manufacturing magnetic antidot arrays using a new technique called AFIR. As a proof of concept we have

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

• can be varied to tune the magnonic spectra and magnetization dynamics in ferromagnetic antidot lattices. Several studies have been focused on the engineering of the coercive field, magnetoresistance and anisotropy properties on domain formation and the magnetization reversal mechanism with the change

• properties and magnonic band structure more efficiently due to the strong interelement exchange and dipolar coupling [28][29]. A remarkable difference in magnetic anisotropies and magnetization reversal mechanisms has been observed in systematically engineered square and binary antidot lattices [30

Magnetic characterization of cobalt nanowires and square nanorings fabricated by focused electron beam induced deposition

• Federico Venturi,
• Gian Carlo Gazzadi,
• Amir H. Tavabi,
• Alberto Rota,
• Rafal E. Dunin-Borkowski and
• Stefano Frabboni

Beilstein J. Nanotechnol. 2018, 9, 1040–1049, doi:10.3762/bjnano.9.97

• , revealing different magnetization states and allowing for step-by-step imaging of magnetization reversal processes. Experimental FEBID was performed in a dual-beam system (FEI Strata DB 235M) using the following electron beam parameters: 1 μs dwell time, 90% overlap and 85 and 130 pA beam currents for

Anchoring Fe₃O₄ nanoparticles in a reduced graphene oxide aerogel matrix via polydopamine coating

• Błażej Scheibe,
• Radosław Mrówczyński,
• Natalia Michalak,
• Karol Załęski,
• Michał Matczak,
• Mateusz Kempiński,
• Zuzanna Pietralik,
• Mikołaj Lewandowski,
• Stefan Jurga and
• Feliks Stobiecki

Beilstein J. Nanotechnol. 2018, 9, 591–601, doi:10.3762/bjnano.9.55

• Limited). The magnetic properties of Fe3O4-containing samples were studies using MPMS-XL SQUID magnetometer (Quantum Design) by performing susceptibility and magnetization reversal measurements. Zero- (ZFC) and field-cooled (FC) susceptibility curves were obtained at 100 Oe with temperature varying from 2

Beyond Moore’s technologies: operation principles of a superconductor alternative

• Igor I. Soloviev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Mikhail Yu. Kupriyanov,
• Alexander L. Gudkov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2017, 8, 2689–2710, doi:10.3762/bjnano.8.269

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

• Discussion Magnetization reversal process of the custom-made probes A non-conventional MFM-based method previously reported [23] was used to measure local hysteresis loops of the MFM probes [24][25] (see section 2 of Supporting Information File 1 for more details). This approach allows for measuring the

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

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

• Institute of Physical Problems, Zelenograd, Moscow 124460, Russia Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow Region, Russia 10.3762/bjnano.6.199 Abstract We present our approach for a consistent, fully quantum mechanical description of the magnetization reversal

• process in natural and artificial atomic systems by means of short magnetic pulses. In terms of the simplest model of a two-level system with a magnetic moment, we analyze the possibility of a fast magnetization reversal on the picosecond timescale induced by oscillating or short unipolar magnetic pulses

• . We demonstrate the possibility of selective magnetization reversal of a superconducting flux qubit using a single flux quantum-based pulse and suggest a promising, rapid Λ-scheme for resonant implementation of this process. In addition, the magnetization reversal treatment is fulfilled within the

Focused particle beam-induced processing

• Michael Huth and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2015, 6, 1883–1885, doi:10.3762/bjnano.6.191

• article by Gian Carlo Gazzadi and Stefano Frabboni [6]. This leads into the important application field of magnetic nanostructures obtained by FEBID. Luis Rodríguez and coworkers present a detailed study on the influence of shape anisotropy and surface oxidation on the magnetization reversal of thin, iron

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

• application of the external magnetic field during the fabrication process. This indicates that during analysis of the hysteresis parameters it is also needed to consider the possible mechanisms of magnetization reversal besides the impact of simple anisotropy. According to the TEM measurements, the

• average sizes of both studied nanomaterials. In single-domain systems, the magnetization reversal can occur via spin rotation [31] and according to the “chain-of-spheres model”, there are two possible mechanisms. One of them called the “parallel rotation mechanism” is related to the simultaneous parallel

• experimental results shown in different publications, the ”fanning mechanism” yields lower coercivity values than the ”parallel rotation mechanism”. Therefore, it is likely that the studied iron nanowires exhibit a lower coercivity because the magnetization reversal follows the “fanning mechanism”, while the

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

• %, thus giving a high ferromagnetic signal. Magneto-optical Kerr characterization indicates that HC decreases for increasing thickness and width, providing a route to control the magnetization reversal field through the modification of the nanowire dimensions. Transmission electron microscopy experiments

• ; focused electron beam induced deposition; iron nanowires; magnetization reversal; magneto-optical Kerr effect; transmission electron microscopy; Introduction The fabrication of magnetic nanostructures in a single lithographic step by focused electron beam induced deposition (FEBID) is currently an

• producing the magnetization reversal. Most of magnetic devices work by producing a voltage output when the magnetization reversal occurs. In the case of cobalt deposits, it was previously found that the coercive field is governed by shape anisotropy [24] due to the polycrystalline microstructure [25], and

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

• that of pure Co, typically. In addition, though the magnetic properties of as-deposited Co-FEBID structures are sufficient for application in Co MFM tips [6] and studying the effects of topological structures on the magnetization reversal process [26], these properties differ from those of pure Co

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

• -optical Kerr effect (MOKE) magnetometer are supported by the magnetic force microscopy imaging and micromagnetic simulations. Keywords: hysteresis; magnetic vortex; magnetization reversal; micromagnetic structure; Introduction Magnetic nanostructures have a wide range of unique properties that

• magnetization reversal in dependence on s. The angle φ, defining the orientation of an applied magnetic field, was counted from the selected x-axis, passing through the centers of the disks. The results are shown in Figure 1b. It was found that the magnetization reversal changes qualitatively. For symmetric

Designing magnetic superlattices that are composed of single domain nanomagnets

• Derek M. Forrester,
• Feodor V. Kusmartsev and
• Endre Kovács

Beilstein J. Nanotechnol. 2014, 5, 956–963, doi:10.3762/bjnano.5.109

• assisted magnetization reversal, as discussed on page 6 of [15] and in [23]). In the stretched elliptical disks or nanowires the perturbation in hx has an insignificant effect and hence can be neglected. The hz component of the field is taken to be zero. We define the phases by the shape of the magnetic

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

• Ulf Wiedwald,
• Felix Haering,
• Stefan Nau,
• Carsten Schulze,
• Herbert Schletter,
• Denys Makarov,
• Alfred Plettl,
• Karsten Kuepper,
• Manfred Albrecht,
• Johannes Boneberg and
• Paul Ziemann

Beilstein J. Nanotechnol. 2012, 3, 831–842, doi:10.3762/bjnano.3.93

• that the MFM-extracted film hysteresis loop is similar to the hysteresis measured by integral techniques such as MOKE. Indeed, this has been demonstrated in reference [25]. Magnetization reversal in arrays of spherical gold particles capped with Co/Pt multilayers An alternative approach towards

• deviation can be understood, in part, by taking into account the distribution of easy axes within the nanocaps following the surface curvature. This necessarily leads to a rather incoherent magnetization reversal process in an individual cap [39], which has also been demonstrated by micromagnetic