Explore the vast range of titles available.

Frustrated spin systems have been first investigated five decades ago. Well-known examples include the Ising model on the antiferromagnetic triangular lattice studied by G H Wannier in 1950 and the Heisenberg helical structure discovered independently by A Yoshimori, J Villain and T A Kaplan in 1959. However, many properties of frustrated systems are still not well understood at present. Recent studies reveal that established theories, numerical simulations as well as experimental techniques have encountered many difficulties in dealing with frustrated systems. This volume highlights the latest theoretical, numerical and experimental developments in the field. The book is intended for post-graduate students as well as researchers in statistical physics, magnetism, materials science and various domains where real systems can be described with the spin language. Explicit demonstrations of formulae and full arguments leading to important results are given.

The origin of unusual anisotropic electronic properties in the spin-density wave state of iron pnictides has conventionally been attributed to the breaking of four-fold rotational symmetry associated with the collinear magnetic order. By using a minimal two-orbital model, we show that a significant portion of the contribution to the anisotropy may come from the Dirac cones, which are not far away from the Fermi level. We demonstrate this phenomenon by examining optical conductivity and quasiparticle interference in the Dirac-semimetallic state with spin-density wave order, and the latter can be obtained by choosing appropriate interaction parameters and orbital splitting between the d xz and d yz orbitals. We further extend this study to investigate the low-energy spin-wave excitations in the Dirac-semimetallic state with spin-density wave order.

We consider the spin wave resonances (SWRs) magnetoelastic excitation and electric detection in a hybrid bulk acoustic wave resonator containing YIG/Pt bilayer. The influence of micrometer and submicrometer yttrium iron garnet (YIG) film thickness on the efficiency of SWR excitation accompanied by a spin pumping from YIG to Pt has been theoretically studied. The frequency and thickness dependencies of inverse spin Hall effect (ISHE) voltage and microwave reflection coefficient are analytically and numerically investigated and discussed. Due to the non-uniform effective magnetic field of elastic nature, the higher SWR modes (both even and odd) can be excited with an efficiency comparable to the efficiency of the fundamental mode at the ferromagnetic resonance frequency. If an integer number of acoustic half-waves fits into the YIG film thickness, forbidden zones arise in the SWR spectrum: at certain thickness values, only even or only odd SWR modes are excited.

In this work, we investigate the structural and dynamic magnetic properties of yttrium iron garnet (YIG) films grown onto gadolinium gallium garnet (GGG) substrates with thin platinum, iridium, and gold spacer layers. Separation of the YIG film from the GGG substrate by a metal film strongly affects the crystalline structure of YIG and its magnetic damping. Despite the presence of structural defects, however, the YIG films exhibit a clear ferromagnetic resonance response. The ability to tune the magnetic damping without substantial changes to magnetization offers attractive prospects for the design of complex spin-wave conduits. We show that the insertion of a 1-nm-thick metal layer between YIG and GGG already increases the effective damping parameter enough to efficiently absorb spin waves. This bilayer structure can therefore be utilized for magnonic waveguide termination. Investigating the dispersionless propagation of spin-wave packets, we demonstrate that a damping unit consisting of the YIG/metal bilayers can dissipate incident spin-wave signals with reflection coefficient R < 0.1 at a distance comparable to the spatial width of the wave packet.

Spin wave propagation is studied through a diffraction grating in a 200 nm thick YIG film by using scanning time resolved magneto‐optic Kerr microscopy (TR‐MOKE) and supported by micromagnetic simulations. Caustic‐like spin wave emission and the hybridization of Damon Eshbach (DE) type spin wave modes within the grating region, depending on the magnetic field and the dimensions of the grating, are observed. Hybridization leads to an increased attenuation length for propagating spin waves and consequently to a transmission stop‐band for spin waves at the grating for a certain magnetic field range. A simple design of a diffraction grating can act as a spin wave stop band for spin waves in the Damon Eshbach geometry if the total internal field is shifted to a value where hybridization between the Damon Eshbach mode and a standing spin wave mode occurs.

Spin-wave devices are regarded as one of the most promising candidates for future computation and data processing. How to manipulate spin-wave propagation is a key issue in realizing the functionality of these of devices. The existing manipulation methods have serious drawbacks for constructing practical spin-wave devices. Here, we propose an approach to harness the amplitude and mode excitation of traveling spin waves by introducing unique micromagnetic textures in a permalloy waveguide directly exchange-coupled to a pair of cobalt nanomagnets. We demonstrate that the imprinted micromagnetic textures, i.e., the 360° domain wall and magnetic buckle, which play different roles in spin-wave manipulation, can be interchanged with each other repeatedly by using a sequence of homogeneous magnetic fields. Moreover, the suggested architecture could easily be tailored to implement fundamental logic-NOT operation. In light of the internal-field profile of the micromagnetic textures, speculation is offered concerning the physical origin underlying the observed spin-wave modulation phenomena.

Spin waves (SWs), being usually reflected by domain walls (DWs), could also be channeled along them. Edge SWs yield the interesting, and potentially applicable to real devices property of broadband spin wave confinement to the edges of the structure. Here, we investigate through numerical simulations the propagation of quasi one-dimensional spin waves in triangle-shaped amorphous YIG (Y 3 Fe 5 O 12 ) micron sized ferromagnets as a function of the angle aperture. The edge spin waves (ESWs) have been propagated over the corner in triangles of 2 microns side with a fixed thickness of 85 nm. Parameters such as superior vertex angle (in the range of 40 ∘ –75 ∘ ) and applied magnetic field have been optimized in order to obtain a higher transmission coefficient of the ESWs over the triangle vertex. We observed that for a certain aperture angle for which dominated ESW frequency coincides with one of the localized DW modes, the transmission is maximized near one and the phase shift drops to π / 2 indicating resonant transmission of ESWs through the upper corner. We compare the obtained results with existing theoretical models. These results could contribute to the development of novel basic elements for spin wave computing. Article Highlights High transmission of edge spin waves through a vertex domain wall in triangular dots. Dependence in the propagation on the local topology of the vertex domain wall. Resonant interaction between the bulk and the local domain wall spin wave modes in the magnetic nanostructure.

Motivated by recent experiments on thin films of the ferromagnetic insulator yttrium-iron garnet (YIG), we have developed an efficient microscopic approach to calculate the spin-wave spectra of these systems. We model the experimentally relevant magnon band of YIG using an effective quantum Heisenberg model on a cubic lattice with ferromagnetic nearest neighbour exchange and long-range dipole-dipole interactions. After a bosonization of the spin degrees of freedom via a Holstein-Primakoff transformation and a truncation at quadratic order in the bosons, we obtain the spin-wave spectra for experimentally relevant parameters without further approximation by numerical diagonalization, using efficient Ewald summation techniques to carry out the dipolar sums. We compare our numerical results with two different analytic approximations and with predictions based on the phenomenological Landau-Lifshitz equation.

Micro-focused Brillouin–Mandelstam light scattering technique and micromagnetic simulations were used to study surface (SSW) and backward volume (BVSW) spin waves (SW) interference under excitation by curvilinear focusing transducers placed oppositely to each other on a top of a tangentially magnetized yttrium iron garnet (YIG) film. It is shown that due to anisotropic propagation, the 2D interference patterns for both SSW and BVSW focused beams are nonreciprocal. Due to chromatic aberration and caustics formation of the focusing transducers, the interference pattern of the focused SW beams depends on the excitation frequency and is sensitive to local nonuniformities in the YIG film. The obtained results demonstrate the possibility to use curvilinear SW focusing transducers for information technologies based on magnonic optics.