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We use the Plane Wave Method to theoretically study thin-film magnonic crystals (MCs) composed of two very common magnetic materials: cobalt and permalloy. In both cases, we consider Co inclusions in the Py matrix and Py inclusions in the Co matrix. An external magnetic field is applied in the plane of the structure, leading to the formation of a demagnetizing field at the interface between the inclusions and matrix. Previous studies have shown that this field strongly affects the spectrum of spin waves, including the position and width of bandgaps. In this study, we exploit the in-plane squeezing of the MC structure to enhance the demagnetizing field. This results in the transfer of low-frequency spin waves from Py to Co, affecting the energy distribution (i.e., the spin-wave profile). The change in the concentration of spin-wave profiles leads to certain peculiarities in the spin-wave frequency spectrum. These include modes repulsion caused by hybridization, which in turn leads to the reordering of modes in the spectrum. • The influence of the demagnetizing field on the excitation of spin waves is studied. • The field is responsible for reordering of spin waves while the structure is squeezed. • This leads to the possibility of designing band gaps by squeezing the structure. [ABSTRACT FROM AUTHOR]

This study investigates the excitation of short-wavelength spin waves (SWs) in nanowire-based spin-Hall nano-oscillators (SHNOs). Using micromagnetic simulations, we study the wavelength of propagating SWs as a function of nanowire width, ranging from 10 to 50 nm, excited in a 1.7 nm-thick CoFeB layer using a pure spin current generated by a 5 nm thin platinum layer via the spin Hall effect. Our results showed that SWs with shorter wavelengths are excited in narrow widths at higher magnetic fields and higher currents. In addition, the wavelength of the propagating waves scales linearly with the width of the nanowire. We attribute the emission of short wavelength due to the quantization of SWs in the nanowire. By reducing the nanowire width, SWs with ultrashort wavelengths are excited at high frequencies, with larger propagation speeds and longer attenuation lengths. Our results show that ultrashort SWs with wavelengths as short as 80 nm can be generated in metallic-based SHNOs, with a group velocity of v g = 1.6 µm/ns and attenuation length of L a t t = 0.6 µm. These findings have significant implications for the scalability of magnonic devices, which could have potential applications in SW-based logic and neuromorphic computing. • Spin Hall nano-oscillators. • Propagating spin waves. • Short wavelength. • Micromagnetic simulations. [ABSTRACT FROM AUTHOR]

• Intense excitation of exchange spin waves in a tangentially magnetized two-layer epitaxial film of iron yttrium garnet. • Mathematical processing of the measured frequencies of resonance peaks for the calculation of the magnetization profile of the doped layer and the modeling of the excitation and propagation processes of exchange spin waves. • Application of mathematical proposed methodology for non-destructive control of the layered structure of epitaxial ferrite structures. The possibility of intense excitation of exchange spin waves in a tangentially magnetized two-layer epitaxial film of iron yttrium garnet is demonstrated. The waves are excited in a thin transition layer at the interface between the ferrite layers, propagate into the doped layer with reduced magnetization, and reflect from its opposite surface. In continuous excitation mode, they can be observed as a series of spin wave resonance peaks. Mathematical processing of the measured frequencies of resonance peaks allows for the calculation of the magnetization profile of the doped layer and the modeling of the excitation and propagation processes of exchange spin waves. The proposed methodology of mathematical processing can be applied for non-destructive control of the layered structure of epitaxial ferrite structures. [ABSTRACT FROM AUTHOR]

A biskyrmion is a conjoined form of two bound skyrmions possessing a total topological charge of 2. Here, by considering a frustrated two-dimensional ferromagnet, we explore a process that allows for splitting biskyrmions into single skyrmions using spin wave excitations, i.e. magnons. Each resultant skyrmion has a topological charge of 1, and they propagate from one another in opposing directions. Furthermore, we investigate both Bloch and Néel types of biskyrmions and find that they exhibit similar splitting processes. • We explore a process that allows for splitting biskyrmions into single skyrmions. • Fractionalization is a topic gaining significant attention in condensed matter systems. • We have used a large amount of magnons to split the biskyrmion. [ABSTRACT FROM AUTHOR]

We have studied theoretically (including computer simulations) dynamical magnetic properties of aggregates of ferromagnetic amorphous nanogranules in the presence of direct exchange between the neighboring granules and random anisotropy fields. It was shown that in such structures there still exist delocalized magnetic excitations similar to magnons in the bulk materials, although at much lower frequencies. The excitations at high frequencies are localized within the corresponding granules. The details of spectrum of these excitations (including structural factors) are discussed. [ABSTRACT FROM AUTHOR]

The available results from the inelastic neutron scattering experiment performed on the quasi-two dimensional spin 1 2 anti-ferromagnetic material La 2 CuO 4 have been analysed theoretically. The formalism of ours is based on a semi-classical like treatment involving a model of an ideal gas of mobile vortices and anti-vortices built on the background of the Néel state, using the bipartite classical spin configuration corresponding to an XY-anisotropic Heisenberg anti-ferromagnet on a square lattice. The results for the integrated intensities for our spin 1 2 model corresponding to different temperatures, show occurrence of vigorous unphysical oscillations, when convoluted with a realistic spectral window function. These results indicate failure of the conventional semi-classical theoretical model of ideal vortex/anti-vortex gas arising in the Berezinskii–Kosterlitz–Thouless theory for the low spin magnetic systems. A full fledged quantum mechanical formalism and calculations seem crucial for the understanding of topological excitations in such low spin systems. Furthermore, a severe disagreement is found to occur at finite values of energy transfer between the integrated intensities obtained theoretically from the conventional formalism and those obtained experimentally. This further suggests strongly that the full quantum treatment should also incorporate the interaction between the fragile-magnons and the topological excitations. This is quite plausible in view of the recent work establishing such a process in XXZ quantum ferromagnet on 2D lattice. The high spin XXZ quasi-two dimensional antiferromagnet like MnPS 3 however follows the conventional theory quite well. [ABSTRACT FROM AUTHOR]

• We explored the effect of magnetic fields on bimeron. • We discovered a new resonance mode of bimeron. • It is found that the resonance frequency of bimeron can be adjusted by magnetic fields. • Our studies can help to open novel research into the spintronics of magnetic bimeron. Magnetic bimeron composed of a meron and an antimeron can be considered as a magnetic skyrmion in the in-plane magnet and have great potential for spintronic devices. Here, we explored the effect of static magnetic fields on the shape of bimeron. It is found that the size of the bimeron can be adjusted by magnetic fields in an anisotropic direction. Then we study the field-tuned spin excitation spectrum of magnetic bimeron. Unlike the common breathing mode and the two rotation modes, novel resonance modes, which can be considered as a combination of the breathing and rocking-rotation modes, are observed. The results presented in this study can help to open novel research into the spintronics of magnetic bimeron. [ABSTRACT FROM AUTHOR]

Within the framework of the kinetic energy driven superconducting mechanism, the dynamical spin response of cuprate superconductors is studied from low-energy to high-energy. The spin self-energy is evaluated explicitly in terms of the collective charge carrier modes in the particle–hole and particle–particle channels, and employed to calculate the dynamical spin structure factor. Our results show the existence of damped but well-defined dispersive spin excitations in the whole doping phase diagram. In particular, the low-energy spin excitations in the superconducting-state have an hour-glass-shaped dispersion, with commensurate resonance that appears in the superconducting-state only , while the low-energy incommensurate spin fluctuations can persist into the normal-state. The high-energy spin excitations in the superconducting-state on the other hand retain roughly constant energy as a function of doping, with spectral weights and dispersion relations comparable to those in the corresponding normal-state. The theory also shows that the unusual magnetic correlations in cuprate superconductors can be ascribed purely to the spin self-energy effects which arise directly from the charge carrier–spin interaction in the kinetic energy of the system. [ABSTRACT FROM AUTHOR]

• Crystal structure suggests formation of magnetic dimers between Cu(II) ions. • Good agreement of experimental data with antiferromagnetic dimer model was observed. • The intra-dimer exchange coupling was estimated J/k B = −5.52 K. • Spin gap ∼11 K is expected to vanish at the critical field 7.8 T. • Absence of phase transition to magnetic long-range order down to 0.4 K. Specific heat, magnetic susceptibility and magnetization of Cu(en) 2 SO 4 single crystal were investigated in the field applied along the b- axis. The analysis of the susceptibility within the Curie-Weiss law indicates the antiferromagnetic nature of the exchange coupling between Cu(II) ions with zJ/k B = −6.4 K. Considering the structure of this material, the formation of magnetic dimers can be expected. Very good description of susceptibility data was achieved using the Heisenberg antiferromagnetic dimer model with intra-dimer coupling J / k B = −5.52 K, effective inter-dimer coupling J ' / k B = −0.3 K and g b = 2.12. The energy gap in the spin excitation spectrum was estimated Δ/ k B ≈ 11 K and corresponding critical field B c b ≈ 7.8 T required for closing the gap. The dimerized nature of magnetic interactions was also confirmed by specific heat and isothermal magnetization data which manifest qualitatively the same behavior as the aforementioned dimer model. The possibility of further low-temperature experiments in the closed gap regime is discussed to obtain more detailed concept of magnetic interactions in this interesting compound. [ABSTRACT FROM AUTHOR]

In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced. • Influence of the demagnetizing field on excitation of spin waves is studied. • The field is responsible for mode-dependent softening of spin waves. • It has also influence on the mode reversal — low-frequency modes are excited in Co. [ABSTRACT FROM AUTHOR]

• Width modes and shape anisotropy are essential for finite width magnetic waveguides. • Width modes help to bend the signal transmission direction in cross-like structures. • Shape anisotropy provides the transmission in the crosses in a wide frequency range. • The inhomogeneity of the waveguide width can filter width modes. • Using a resonator as a waveguides junction can help for effective signal transfer. Microwaveguides for spin waves based on yttrium iron garnet films and cross-like structures built on such waveguides are experimentally studied. Effects of the waveguides geometry, location of the microantennas for excitation and detection of the spin waves, and geometry of the waveguides junctions on the spin wave excitation and propagation efficiency are discussed. [ABSTRACT FROM AUTHOR]

• The breaking of topological protection is realized by applying microwave field. • This process is assisted by the excitation of spin wave modes of target skyrmions. • The excitation of spin wave modes results from the resonance of annular domain. Target skyrmions have been attracting intensive attention as the building block of spintronic devices. However, due to the topological protection of these magnetic textures, an extra driving force is needed to realize the transition between different magnetic textures. Herein, we achieve the transition of these magnetic textures with the breaking of topological protection by applying perpendicular microwave magnetic field, which is assisted by the excitation of breathing modes and hybridized modes (combination of breathing modes and radial spin wave modes). Another distinct resonance mode originating from the interaction of hybridized mode and breathing mode is also found, which is excited by isolated annular domain in different positions of nanodisks. Our results provide an insight for the understanding of complex dynamic behaviors in magnetic textures and the designing of spintronics devices. [ABSTRACT FROM AUTHOR]

Magnons are the elementary excitations of the magnetic order that carry spin, momentum, and energy. Here we compare the magnon with the ferron , i.e. the elementary excitation of the electric dipolar order, that transports polarization, momentum, and energy in ferroelectrics. [ABSTRACT FROM AUTHOR]

Abstract: Optical excitation of electron spin orientation and spin coherence is studied associated with the state-mixing due to the coupling of the anisotropic fine-structure and Zeeman energies. An adiabatically-induced magnetization is none of the consequence of either the angular-momentum transfer from light to matter or the Boltzmann population difference in the presence of magnetic field. Different types of the state-mixings are described with respect to the combination of the Zeeman sublevels. Experiment has been carried out for a sample of ruby at room temperature. Dependences of the intensity of the induced magnetization on wide ranges of the strength and direction of the magnetic field have shown excellent agreement with density-matrix calculation of the spin expectation values. Consideration of the spin state-mixing also accounts for the polarization-insensitive optical excitation of electron spin orientation previously reported for spin ensembles in poly-crystal and solution. [Copyright &y& Elsevier]

Abstract: We investigated the influence of strong single-ion anisotropy, exceeding exchange interaction, and frustrated exchange interaction on spin-wave excitation spectra and phase states using the Hubbard operators’ technique, allowing the exact account of single-ion anisotropy. The results show that both the homogeneous phases (ferromagnetic and quadrupolar) and the spatially inhomogeneous phase (spiral structure) are possible in the 3D magnetic crystal. The region of existence of the spiral structure is considerably smaller than that in the analogues system, but with weak single-ion anisotropy. The situation is more complex in the 2D system; another spatially inhomogeneous state (the domain structure) can be realized in addition to the spiral magnetic structure. The phase diagrams for both the 3D and 2D systems were plotted. [Copyright &y& Elsevier]

Abstract: We have investigated the hyperfine interaction in Co2SiO4 by inelastic neutron scattering with a high resolution back-scattering neutron spectrometer. The energy spectrum measured from a Co2SiO4 powder sample revealed inelastic peaks at at T=3.5K on both energy gain and energy loss sides. The inelastic peaks move gradually towards lower energy with increasing temperature and finally merge with the elastic peak at the electronic magnetic ordering temperature . The inelastic peaks have been interpreted to be due to the transition between hyperfine-split nuclear level of the 59Co isotopes with spin . The temperature dependence of the energy of the inelastic peak in Co2SiO4 showed that this energy can be considered to be the order parameter of the antiferromagnetic phase transition. The determined hyperfine splitting in Co2SiO4 deviates from the linear relationship between the ordered electronic magnetic moment and the hyperfine splitting in Co, Co–P amorphous alloys and CoO presumably due to the presence of unquenched orbital moment. These results are very similar to those of CoF2 recently reported by Chatterji and Schneider [7]. [Copyright &y& Elsevier]

Abstract: The magnetization dynamics of magnetic nanostructures magnetized at an arbitrary out-of-plane angle is investigated with the spin-wave formalism. The magnetic excitations driven by a spin-polarized direct current are considered to be standing spin-wave modes appropriate for nanopillar structures. The spin waves grow exponentially above a certain critical value of the current density and their post-threshold nonlinear dynamics leads to magnetization oscillations in the microwave range. Due to demagnetizing fields, the current-driven excitation strongly depends on the direction of the applied external magnetic field. In order to calculate the microwave oscillation frequency we derive an equation of motion for the spin-wave amplitude as a function of the out-of-plane angle of the applied field. The results are compared with recent experimental data as well as with another theoretical approach. [Copyright &y& Elsevier]

Abstract: Recent inelastic neutron scattering experiments in and single crystals measured spin wave excitations at low temperatures. These two heavy fermion compounds exhibit antiferromagnetic (AF) long-range order, but a strong competition between the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction and Kondo effect is evidenced by their nearly equal Néel and Kondo temperatures. Our aim is to show how magnons such as measured in the AF phase of these Ce compounds, can be described within a microscopic Heisenberg–Kondo model introduced by Iglesias, Lacroix and Coqblin, previously applied to study the non-magnetic phase. The model includes the Ce-4f local moments, assumed in AF order, and Kondo-coupled with the electrons in the conduction band, where we also allow for Hubbard correlation possibly inducing an AF state. We consider competing RKKY (Heisenberg-like ) and Kondo () AF couplings. Carrying on a series of unitary transformations, we perturbatively derive a second-order effective Hamiltonian which, averaged onto the AF electron ground state, describes the AF spin wave excitations, renormalized by their interaction with correlated itinerant electrons. We numerically study how the different parameters of the model influence the renormalization of the magnons, yielding useful information for the analysis of inelastic neutron scattering (INS) experiments in AF heavy fermion compounds. We also compare our results with the available experimental data, finding good agreement with the spin wave measurements in cubic . [Copyright &y& Elsevier]

Abstract: We consider the one-dimensional quantum disordered Heisenberg ferromagnetic chain model with long-range correlated exchange couplings and study the nature of collective two-spin excitations. By using an exact diagonalization of the Hamiltonian in the two-spin flip subspace, we compute the spin wave participation number to characterize the localized or delocalized nature of the two-magnon states. For strongly correlated random exchange couplings, extended two-spin excitations with finite energy appear. Integrating the time-dependent Schroedinger equation, we follow the time-evolution of an initially localized two-spin state. We find that, associated with the emergence of extended spin waves, the wave-packet mean-square displacement develops a ballistic spread. Further, the single-spin wave-packet acquires an asymmetric profile due to the kinematic interaction between the excited spins. [Copyright &y& Elsevier]

Abstract: The influence of a uniform external magnetic field on the dynamical spin response of cuprate superconductors in the superconducting state is studied based on the kinetic energy driven superconducting mechanism. It is shown that the magnetic scattering around low and intermediate energies is dramatically changed with a modest external magnetic field. With increasing the external magnetic field, although the incommensurate magnetic scattering from both low and high energies is rather robust, the commensurate magnetic resonance scattering peak is broadened. The part of the spin excitation dispersion seems to be an hourglass-like dispersion, which breaks down at the heavily low energy regime. The theory also predicts that the commensurate resonance scattering at zero external magnetic field is induced into the incommensurate resonance scattering by applying an external magnetic field large enough. [Copyright &y& Elsevier]

The t - J - U model of high- T c copper-oxide superconductors incorporates both the on-site Coulomb repulsion and kinetic exchange interaction and yields a semi-quantitative description of the static properties of those materials. We extend this analysis to dynamic quantities and address collective spin- and charge excitations in the correlated metallic state of the t - J - U model. We employ VWF+ 1 / N f approach that combines the variational wave function (VWF) approach with the expansion in the inverse number of fermionic flavors (1 / N f ). It is shown that the resonant (paramagnon) contribution to the dynamic magnetic susceptibility remains robust as one interpolates between the Hubbard- and t - J -model limits, whereas the incoherent continuum undergoes substantial renormalization. Energy of the collective charge mode diminishes as the strong-coupling limit is approached. We also introduce the concept of effective kinetic exchange interaction that allows for a unified interpretation of magnetic dynamics in the Hubbard, t - J , and t - J - U models. The results are discussed in the context of recent resonant inelastic x -ray scattering experiments for the high- T c cuprates. [ABSTRACT FROM AUTHOR]

Abstract: Pr3+ ion crystal field (CF) excitations in PrMnO3 single crystals have been studied by infrared transmission, in the 1800–8000cm−1 range, as a function of temperature and applied magnetic field up to 13T. No noticeable frequency shifts which might occur below T N∼100K, as a result of the antiferromagnetic transition, are observed in the Pr3+ CF levels. A set of CF parameters that fit the experimental levels as well as the low temperature Pr3+ magnetic moment in PrMnO3 has been determined. [Copyright &y& Elsevier]

Abstract: Whereas there has been a general consensus for some time that Ising spin glasses have a transition at finite temperature in zero field in three dimensions, there has not been general agreement on two other questions concerning phase transitions in spin glasses in three dimensions: (i) is there a transition at finite temperature in isotropic vector spin glasses (such as Heisenberg), and (ii) is there a phase transition (AT line) in a magnetic field in Ising spin glasses? By using Monte Carlo simulations, analyzed with finite-size scaling, I will argue that the answer to the first question is “yes”, and to the second question is “no”. [Copyright &y& Elsevier]

Abstract: Recent studies on the spin and the chirality orderings of the three-dimensional Heisenberg spin glass (SG) and related systems are reviewed with particular emphasis on the possible spin–chirality decoupling phenomena. Chirality scenario of real SG transition and its experimental consequence on the ordering of Heisenberg-like SGs are discussed. [Copyright &y& Elsevier]

Abstract: We present dynamical magnetic properties in the presence of a static bias field on the 3d Ising spin glass (SG) . It exhibits critical dynamics only in zero field, suggesting that there is no Almeida–Thouless line for Ising SGs. Instead a dynamical crossover scenario, based on the real-space droplet picture, can explain the in-field magnetic properties. We also interpret the glassy nature of the field-cooled magnetization in accordance with the real-space picture. [Copyright &y& Elsevier]

Abstract: Quantum tunneling of magnetization of ions doped in glass matrix has been investigated. An adiabatic condition has been achieved by using a fast sweeping magnetic field. The forbidden zero field quantum tunneling is observed even in the dilute limit, where the dipolar coupling is negligible. The tunneling gap is independent of the doping concentration and the value is evaluated to be 20mK. As the origin of this small tunneling gap, the hyperfine coupling with the on-site nuclear spin is considered. It is found that the tunneling is allowed because the total spin is integer in this coupled system of and . [Copyright &y& Elsevier]

Abstract: The method of discrete Fourier transform (DFT) is applied to obtain the exact one- or bi-magnonic states in several finite one-dimensional spin systems. The advantage of DFT method, compared to Bethe ansatz, is that no assumption is made on the form of the wave function and that its limit of infinite system reduces to the standard approach to excitation spectra in condensed matter. So the method has, in principle, no limitation on lattice dimensionality and its physical interpretation is relatively transparent. It is demonstrated that the two approaches (DFT and BA) give identical results for the solution of the Schrodinger equation on the 1D lattice, although the structure of the methods is rather different. The excitation spectrum of the XXZ chain with arbitrary end fields is analyzed in detail and an analogy with atomic wires is briefly discussed. [Copyright &y& Elsevier]

Abstract: We conducted a detailed comparative study of thermal stability properties over a thermal excitation of switching of the free layer in a magnetic tunnel junction (MTJ) with Ni81Fe19, Co90Fe10, and synthetic antiferromagnetic (Syn-AF) free layers with several strengths of interlayer exchange coupling (J EX). The thermal stability properties were investigated using the junction magnetoresistance of current-perpendicular MTJ devices with a word line as probes. The observed sweep-rate-dependent coercivities were analyzed using the Sharrock formula. The results confirmed strong J EX dependence on thermal stability parameters in Syn-AF free layers. The values of for MTJs with Syn-AF free layers decreased with a decrease in the strength of J EX, and the increase in the effective volume of the Syn-AF free layer disappeared at . The Syn-AF free layer with J EX>0.52erg/cm 2 is relevant for high-density spin electronic nanodevices with a low aspect ratio. [Copyright &y& Elsevier]

Abstract: The magnetic excitation properties in the [Ni1− x Fe x /Cu] alloy super-lattices with and are investigated within the linear spin wave theory framework. The excitation spectra and the magnetization are calculated using Green''s function method. The results show that for each wave vector value there are N coupled modes for a super lattice with N planes. The alloying effect leads to an exchange and magnetic stability reinforcement, as confirmed by the exchange integral values deduced from a satisfactory comparison between the calculated magnetization and the measured one in presence of an applied magnetic field. [Copyright &y& Elsevier]

Abstract: To clarify the contributions of spin-polarized current and spin accumulation to the current-induced magnetization switching, the effects of the top electrode size of the magnetic nanopillar are investigated both theoretically and experimentally. Theoretical calculation demonstrates that the spin-polarized current and the spin accumulation can be adjusted in opposite directions by modifying the size of the top electrode. Increase in the size of the top electrode suppresses the spin accumulation but enhances the spin-polarized current inside the nanopillar. On the other hand, it is shown experimentally that the nanopillar with a wide top electrode exhibits small critical switching current compared to the nanopillar with a narrow top electrode. The results suggest that the spin-polarized current contributes to the current-induced magnetization switching dominantly over the spin accumulation. [Copyright &y& Elsevier]

Abstract: A longstanding theoretical prediction is the orientation of spins by an electrical current flowing through low-dimensional carrier systems of sufficiently low crystallographic symmetry. Here we show by means of terahertz transmission experiments through two-dimensional hole systems a growing spin orientation with an increasing current at room and liquid nitrogen temperatures. [Copyright &y& Elsevier]

Abstract: Magnetic damping has been studied in magnetic double layers using a network analyzer (NA) with a coplanar transmission line. The magnetic films consisted of ultrathin crystalline films of Fe separated by an Au spacer. The films were deposited on GaAs(001) substrates using the molecular beam epitaxy (MBE) technique. NA-ferromagnetic resonance (NA-FMR) measurements were carried out along the magnetic hard axis, allowing one to follow the frequency FMR linewidth down to the 1GHz range of frequencies. It will be shown that the FMR linewidth in the NA-FMR measurements is not entirely described by Gilbert damping. The additional contribution in the frequency linewidth increases with decreasing frequency, and is most likely caused by dipolar fields associated with an inhomogeneous RF field around the coplanar transmission line. [Copyright &y& Elsevier]

Abstract: We calculate the temperature-dependent energy gap in the magnetic excitations spectrum of the two-dimensional antiferromagnet in the presence of a staggered magnetic field, using the nonlinear sigma model. [Copyright &y& Elsevier]

Abstract: We present C-NMR investigations of the S = antiferromagnetically coupled Heisenberg chain system [CuPM(NO)(HO)], (PM==pyrimidine). For this material, as result of the Dzyaloshinskii–Moriya interaction and an alternating g-tensor, the ground state is characterized by a giant static spin canting and an anisotropic magnetic field-induced spin excitation gap. We measured the spin–lattice relaxation rate at three inequivalent carbon sites in the pyrimidine molecule as function of temperature. From these studies we deduce the magnetic excitation spectrum of copper pyrimidine dinitrate at a constant applied magnetic field of 9.3T. The experimental data are discussed in context with recent ESR investigations, which have been interpreted in terms of breather, soliton and multi-particle excitations based on the quantum sine-Gordon field theory. [Copyright &y& Elsevier]

Temperature dependence of the spontaneous magnetization and its derivatives reveal the existence of second-order spin reorientation reform (SOSRR) in the two-sublattice ferrimagnetic system. The variation of the competition between two sublattice moments and that between two sublattice anisotropies gives rise to eight types of temperature dependences of the spontaneous magnetization. An example of the phase diagram for the conditions for different types of thermal curves was delineated by means of numerical calculation. Phase diagrams related to SOSRR transitions were depicted by analyzing the exchange-anisotropy flow in the exchange-anisotropy space. [Copyright &y& Elsevier]

The exact Callen–Suzuki statistical identities for the Ising model with arbitrary spin S are discussed. In particular, the recursion method for obtaining the arbitrary-order moments is shown. The concept of projection operator is employed for studies of the reduction of the high-order moments, as well as for the van der Waerden identities. Also, the integral operator method is extended for the model in question. The obtained exact formulas are discussed from the point of view of their practical applicability. [Copyright &y& Elsevier]

An effective-field theory with correlations, that correctly incorporates the single-site kinematic relations of the spin operators, is applied to the mixed spin-1 and spin-3/2 Ising system with different single-ion anisotropies. The phase diagrams are investigated numerically for the square and simple cubic lattices and results in some aspects are crucially different to those obtained by using an approximate Van der Waerden identity for spin-3/2 Ising system with different single-ion anisotropies. The phase diagrams are investigated numerically for the square and simple cubic lattices and results in some aspects are crucially different to those obtained by using an approximate Van der Waerden identity for spin-3/2 as well as in the case of the honeycomb lattice. The thermal dependence of the magnetization is studied, and the existence and dependence of a compensation point on single-ion anisotropies is also investigated for the square lattice. [Copyright &y& Elsevier]

We have investigated experimentally the spin transport properties in ferromagnetic–superconductor–ferromagnetic double-barrier tunnel junctions. The transport measurements were conducted at mK temperatures with magnetic fields applied along the leads. When the magnetic moments of the two ferromagnetic leads were in opposite orientations (i.e. antiferromagnetic alignment), majority of the spins accumulated in the superconducting island. This was evidenced by a suppression of the superconducting gap. [Copyright &y& Elsevier]

[Display omitted] • A concept of a tunable optical excitation of spin waves in a ferromagnetic film with Néel domain wall is presented. • The fluence of the femtosecond laser pulse and its position with respect to the domain wall affect the frequencies of the excited spin waves. • The presence of the domain wall plays a crucial role in the control of the spin waves' spectrum. We present a concept of a tunable optical excitation of spin waves and filtering their spectra in a ferromagnetic film with 180 ° Néel domain wall. We show by means of micromagnetic simulation that the fluence of the femtosecond laser pulse and its position with respect to the domain wall affect the frequencies of the excited spin waves, and the presence of the domain wall plays crucial role in control of the spin waves' spectrum. The predicted effects are understood by analyzing the changes of the spin waves' dispersion under the impact of the laser pulse. [ABSTRACT FROM AUTHOR]

• The dynamical structure factor for quantum spin 1/2 antiferromagnet in a magnetic field. • Quantum 2D-AFM may demonstrate three modes of spin excitations in a magnetic field. • The three peak structure should be observed along the magnetic Brillouin zone boundary. We predict that spin-waves in an ordered square quantum antiferromagnet in a magnetic field (h) perpendicular to antiferromagnetic plane may demonstrate three modes of spin excitations. Starting from the self-consistent rotation-invariant Green's function method, a new mean-field theory is constructed for h ≠ 0. The method preserves the translational and the axial symmetries, and provides exact fulfillment of the single-site constraint for each of the three modes. We examine the dynamical structure factors S α α (k , ω) , α (β) = x, y, z. It is shown, that the introduction of h leads to the hybridization of two degenerate spin modes due to the appearance of a nondiagonal on α , β spin-spin Green's functions. The comparison of the theory with the exact diagonalization study and with results on inelastic neutron scattering experiments is discussed at T = 0. We discuss also the correspondence of the present theory to the existing theories, which allow only two spin excitations modes for the total S (k , ω). [ABSTRACT FROM AUTHOR]

Abstract: We observed that AC susceptibility of a weak random anisotropy magnet (weak RAM), amorphous NdGdFe, strongly depends on the excitation field, h 0; with increasing h 0 from 0.1 to 1Oe, both Re χ 0 and Im χ 0 become several times larger, and the ratio of Im χ 0 to Re χ 0 increases from about 0.1 to 1.0, suggesting that the average relaxation time becomes much longer by h 0. In addition, peak temperature width of Re χ 0 broadens extremely and the peak temperature of Im χ 0 shifts to lower temperature side. A characteristic relaxation time τ c, obtained for different h 0 by using the Cole–Cole analysis, has two anomalies at T c1 and T c2 with keeping a fairly long relaxation time between T c1 and T c2. These phenomena in a weak RAM were discussed in terms of the free energy structure with small height of barriers comparable with h 0. [Copyright &y& Elsevier]

Abstract: Measurements of the magnetic excitations in the dilute, short-ranged interaction, anisotropic, antiferromagnet , with magnetic concentration , were made using pulsed-field spectroscopy and inelastic neutron scattering. [Copyright &y& Elsevier]

Abstract: We have theoretically studied the spin ordering of using a Monte Carlo method. We found the spin glass phase occurs for in addition to the ferromagnetic phase for . An obtained phase diagram is in agreement with the experimental one fairly well. [Copyright &y& Elsevier]

Abstract: We review the main properties of spin waves condensation to a coherent quantum state, named homogeneously precessing domain (HPD). We describe the long range coherent transport of magnetization by spin supercurrent in antiferromagnetic superfluid . This quantum phenomenon was discovered 20 years ago. Since then, many magnetic extensions of superconductivity and superfluidity have been observed: spin Josephson phenomena, spin-current vortices, spin phase slippage, long distance magnetization transport by spin supercurrents, etc. Several new supercurrent phenomena have been discovered, like magnetically excited coherent quantum states, NMR in the molecular Landau field, spin-current turbulence, formation of stable non-topological solitons, etc. [Copyright &y& Elsevier]

Abstract: We have studied magnetic excitations in the coupled spin dimer system Tl by means of Raman scattering. A broad two-magnon Raman band extending from to about is observed at low temperatures, where is the spin-gap energy. With increasing nonmagnetic impurity Mg, the intensity of the broad Raman band weakens and its onset energy, 2, shifts to higher energy. The quasi-elastic scattering appears and the onset of the two-magnon Raman band gets smeared when . The Raman spectrum hardly changes when a magnetic field is applied, which indicates a creation of a pair of triplets whose total S is zero in the second-order Raman process. [Copyright &y& Elsevier]

Abstract: Large As/V substitutions in result in planar Dy spins ordering antiferromagnetically in the presence of strong random anisotropy disorder. Neutron measurements on show the development of sharp but not resolution-limited magnetic diffraction peaks below 1.6K. Magnetic ordering appears to equilibrate on a time scale of hours as the temperature is reduced in small steps, but, remarkably, the time scale is nearly independent of temperature. [Copyright &y& Elsevier]

Abstract: Magnetic phase transitions under hydrostatic pressures in spin gap systems and KCu were investigated by magnetization measurements. The present doped systems exhibit impurity-induced magnetic orderings. With increasing pressure, ordering temperature increases. With a further increase in pressure, the present systems undergo phase transitions to uniform antiferromagnetic phases due to the closing of the triplet gap in the intact dimers. The crossover from the impurity-induced ordered phase to the uniform antiferromagnetic phase occurs at for . [Copyright &y& Elsevier]

Abstract: Two new hetero tri-nuclear oxalates (NH4)8[Fe2Co(C2O4)8]·6H2O and [Fe2Co(C2O4)2(OH)4]·2H2O have been synthesized. The compound presented opposite behaviour in ac-susceptibility measurements, different frustration level and spin–orbit coupling in magnetization ones. The Mössbauer approach pointed to local interactions governed by metal-oxalate strongly coupled unit. The data were interpreted in terms of role of positive (NH4) or negative (OH) bridging ligands on general magnetic properties. [Copyright &y& Elsevier]

Abstract: We study magnetic ordering in non-equilibrium processes in temperature cycling where first the photoinduced saturated magnetic ordered state is prepared, and then the system is warmed up to a certain temperature (say ) and it is cooled down to the initial temperature. Using a generalized model which describes both spin-crossover transition and magnetic transition, we show that depending on the value of , the critical temperature of magnetization and its saturated value change, which reproduces qualitatively the experimental results of magnetic ordering. It is found that the properties of dilution of magnetic sites affect the magnetic ordering. [Copyright &y& Elsevier]

Abstract: Magnetic interactions in a new copper(II) carboxylate complex {Cu2(O2CH)4}{Cu(O2CH)2(2-methylpyridine)2} were studied with the aim of better understanding magneto-structural correlation in a quasi 1-D spin arrangement. The only magnetic ions in the structure (Cu2+, S=1/2) form chains of dimer–monomer units. Copper ions in dimers are bridged by four carboxylate groups with an antiferromagnetic exchange coupling J/k B=−320K. Susceptibility of the monomer copper ions follows Curie 1/T law down to 20K. Below 20K the susceptibility abruptly decreases due to the antiferromagnetic coupling between monomers. [Copyright &y& Elsevier]