6 research outputs found
Generalized Global Defect Solutions
We investigate the presence of defect structures in generalized models
described by real scalar field in space-time dimensions. We work with
two distinct generalizations, one in the form of a product of functions of the
field and its derivative, and the other as a sum. We search for static
solutions and study the corresponding linear stability on general grounds. We
illustrate the results with several examples, where we find stable defect
structures of modified profile. In particular, we show how the new defect
solutions may give rise to evolutions not present in the standard scenario in
higher spatial dimensions.Comment: RevTex, 10 pages, 2 figures; version to appear in EPJ
Entrapment of a Network of Domain Walls
We explore the idea of a network of defects to live inside a domain wall in
models of three real scalar fields, engendering the Z_2 x Z_3 symmetry. The
field that governs the Z_2 symmetry generates a domain wall, and entraps the
hexagonal network formed by the three-junctions of the model of two scalar
fields that describes the remaining Z_3 symmetry. If the host domain wall bends
to the spherical form, in the thin wall approximation there may appear
non-topological structures hosting networks that accept diverse patterns. If
Z_3 is also broken, the model may generate a buckyball containing sixty
junctions, a fullerene-like structure. Applications to cosmology are outlined.Comment: Revtex, 4 pages, 2 ps figures; version to appear in Phys. Rev. D,
Rapid Communicatio
Quantum paradigm of the foldover magnetic resonance
The explosive development of quantum magnonics requires the consideration of several previously known effects from a new angle. In particular, taking into account the quantum behavior of magnons is essential at high excitations of the magnetic system, under the conditions of the so-called phenomenon of “foldover” (bi-stable) magnetic resonance. Previously, this effect was considered in the quasi-classical macrospin approximation. However, at large angles of magnetization precession, the magnon density exceeds the critical value for the formation of a magnon Bose condensate (mBEC). Naturally, this purely quantum phenomenon does not exist in the classical approximation. In addition, mBEC leads to superfluid transfer of magnetization, which suppresses the macroinhomogeneity of the samples. The experiments presented in the article show that quantum phenomena well describes the experimental results of nonlinear magnetic resonance in yttrium iron garnet. Thus, we remove the questions that arose earlier when considering this effect without taking into account quantum phenomena. This discovery paves the way for many quantum applications of supermagnonics, such as the magnetic Josephson effect, long-range spin transport, Q-bits, quantum logic, magnetic sensors, and others
Nonlinear FMR spectra in yttrium iron garnet
Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at
room temperature. The ferromagnetic resonance (FMR) spectra were obtained for one-layer
single crystal YIG films for different values of the applied microwave power. Nonlinear FMR
spectra transformation by the microwave power increasing in various directions of magnetic
field sweep was observed. It is explained by the influence of the demagnetization action of
nonequilibrium magnons
Long-Lived Induction Signal in Yttrium Iron Garnet
© 2020, Pleiades Publishing, Inc. The results of the experiments on an yttrium iron garnet film have been reported, demonstrating two types of long-lived free induction signals. The first type corresponds well to signals appearing because of the superfluid transfer of magnons, which was previously detected in antiferromagnetic superfluid 3He-B. The second, ultra-long-lived, signal also has a number of properties of coherent precession. However, it is fundamentally different from the ultra-long-lived signal in 3He-B. The mechanism of formation of the ultra-long-lived signal in yttrium iron garnet has not yet been theoretically explained