Морфологічні показники продихів і склад кутикулярних восків листків липи повстистої (Tilia tomentosa Moench) за умов освітлення та затінення

Objective – to determine the differences in the morphological parameters of stomata and the component composition of cuticular waxes of silver linden (Tilia tomentosa Moench) leaves under conditions of lighting and shading in the crown of a tree. Material and methods. The sun-adapted and shadeadapted fully developed leaves of silver linden were selected as the test objects in our study. The component composition of the cuticular waxes was investigated by gas chromatography method, and stomata size and quantity values were determined on the epidermal imprints of the abaxial side of leaves. Results. The adaptive changes in leaves of the alien invasive plant species silver linden were established under conditions of increasing light intensity and temperature and reducing air humidity. Conclusion. The leaf surface area, leaf weight per unit area, density of stomata, and the content of the long chain components of the cuticular waxes increase, the length and the width of stomata decrease under conditions of lighting.Мета – визначити відмінності у морфологічних показниках продихів і складі кутикулярних восків листків липи повстистої (Tilia tomentosa Moench) в умовах освітлення та затінення. Матеріал та методи. Для дослідження відбирали оптимально розвинуті непошкоджені листки липи повстистої. Склад поверхневих восків вивчали методом капілярної газової хроматографії. Кількість і розмір замикальних клітин продихів визначали на відбитках епідермісу на абаксіальному боці листків рослин. Результати. Встановлено адаптивні зміни в листках липи повстистої в умовах збільшення інтенсивності освітлення і температури та зниження вологості повітря. Висновок. За умов освітлення збільшується площа листкової пластинки, маса одиниці площі листків, щільність продихів та вміст довголанцюгових компонентів у складі кутикулярних восків, а довжина і ширина продихів зменшуються порівняно із затіненими листками

Formation of Bose–Einstein magnon condensate via dipolar and exchange thermalization channels

Thermalization of a parametrically driven magnon gas leading to the formation of a Bose–Einstein condensate at the bottom of a spin-wave spectrum was studied by time- and wavevector-resolved Brillouin light scattering spectroscopy. Two distinct channels of the thermalization process related on dipolar and exchange parts of a magnon gas spectrum are clearly determined. It has been found that the magnon population in these thermalization channels strongly depends on applied microwave pumping power. The observed magnon redistribution between the channels is caused by the downward frequency shift of the magnon gas spectrum due to the decrease of the saturation magnetization in the course of injection of parametrically pumped magnons

Bullets and droplets: Two-dimensional spin-wave solitons in modern magnonics

In this review we consider theoretical and experimental results related to the properties of two-dimensional spin-wave (SW) solitons, so-called SW bullets and SW droplets. Such nonlinear self-localized SW modes possess very interesting physical properties, and could have practical applications in modern and future magnonics and spintronics. The experimental and theoretical results presented in this review have undeniably proven the existence of SW bullets in magnetic films and confined magnetic nanostructures (magnetic nanocontacts), and have elucidated the essential distinctions between the properties of the one-dimensional nonlinear SW solitons, two-dimensional nonlinear SW bullets and linear spin wave packets, as well as the possibility of self-generation, parametrical excitation, and phase-conjugation of the SW bullets, similar to the case of the conventional linear spin waves. Also, in this review we presented experimental results demonstrating the nucleation, dynamics, and annihilation of two-dimensional strongly nonlinear SW “droplets” in spin-torque-driven magnetic nanocontacts. The properties of these exotic nonlinear objects are analyzed using recently developed theoretical models and illustrated by micromagnetic numerical simulations

Spin-wave tunnelling through a mechanical gap

We report on the experimental and theoretical investigation of spin-wave tunnelling through a mechanical gap in a ferromagnetic film. Samples with different gap widths were fabricated and the transmission of spin-wave pulses through the gaps was studied. Transmission through the gaps is possible due to the long-range character of the dipole-dipole interaction underlying dynamics of long-wavelength spin waves. By comparing our experimental results with the developed theoretical model, we demonstrate, that the local inhomogeneity of the static magnetisation and the internal field has a significant impact on the transmission

Microscopic spin-wave theory for yttrium-iron garnet films

75.10.Jm Quantized spin models, 75.30.Ds Spin waves, 05.30.Jp Boson systems,

Magnons coherent transmission and heat transport at ultrathin insulating ferromagnetic nanojunctions

A model calculation is presented for the magnons coherent transmission and corresponding heat transport at insulating magnetic nanojunctions. The system consists of a ferromagnetically ordered ultrathin insulating junction between two semi-infinite ferromagnetically ordered leads with ideally flat crystal interfaces. The ground state of the system is depicted by an exchange Hamiltonian neglecting smaller dipolar and anisotropy terms. The spin dynamics are analyzed using the equations of motion for the spin precession displacements, valid in the limit of low temperatures compared to an order-disorder transition temperature characteristic of the system. The coherent transmission and reflection spectra at the nanojunction boundary are calculated in the Landauer-Buttiker formalism using the matching theory, for all the magnons in the lead bulk, at arbitrary angles of incidence on the boundary, and for variable temperatures. The model calculations yield the thermal conductivity κm due to the magnons coherent transmission between the two leads maintained at slightly different temperatures. The model is general, and is applied in particular to the Fe/Gd/Fe system to calculate the coherent transmission of magnons and their thermal conductivity at the junction boundary, for different thicknesses of the Gd junction and its corresponding magnetic order. The calculated results elucidate the comparison between the heat transport from magnons with that in parallel channels from electrons and phonons, at the nanojunction boundary