Spin-wave resonance studies on chemical vapor deposited YIG films

Abstract

We report perpendicular spin-wave resonance measurements in single crystal YIG films a t 77 K and several frequencies. For films of thickness 0.9 W m the SWR mode positions follow a quadratic (n2) dependence. For 0.37 pm thick films sizeable deviations appear a t n > 4. Further, these deviations increase with microwave frequency. Effects of annealing these films a t several temperatures between 700 and 1250 "C have also been studied. It is suggested that the data can be roughly understood by invoking a diffusion region, of varying magnetization, a t the YIG-substrate interface.L'article d6crit des etudes d'ondes de spin en resonance perpendiculaire B plusieurs frbquences sur des couches monocristallines d'YIG. Pour des couches d'6paisseur 0,9 um. les positions des modes de resonance suivent une loi quadratique (n2). Pour des couches d'6paisseur 0,37 pm, des deviations assez grandes apparaissent pour n > 4. De plus ces deviations augmentent avec la frequence microonde. On a aussi 6tudi6 l'effet sur ces films de recuits B diffbrentes tempdratures entre 700 et 1250 "c. On suggbre que les rbsultats peuvent Btre assez bien expliquhs en postulant une region de diffusion, d'aimantation variable, B l'interface YIG-substrat.

Skyrmionic spin Seebeck effect via dissipative thermomagnonic torques

“…These discoveries enabled unprecedented degree of control in magnetic informationstorage devices in which the magnetization can be flipped at will [12] or the domain wall can be moved in order to change the magnetization configuration [13]. Sizable coupling of spin to thermal flows [14] leads to yet another knob by which we can control magnetization and magnetic textures such as domain walls [15][16][17][18] [25], where the magnetization dynamics have low dissipation as coupling to electron continuum is absent [18,26]. At the same time, even at relatively low temperatures, thermal magnons have very small wavelength and thus can be treated as particles on the scale of magnetic texture [18,27].…”

“…Particularly strong coupling between heat flows carried by magnons and magnetic textures is expected in magnetic insulators such as Cu 2 OSeO 3 [23], BaFe 1−x−0.05 Sc x Mg 0.05 O 19 [24], and Y 3 Fe 5 O 12 [25], where the magnetization dynamics have low dissipation as coupling to electron continuum is absent [18,26]. At the same time, even at relatively low temperatures, thermal magnons have very small wavelength and thus can be treated as particles on the scale of magnetic texture [18,27].…”

Landau-Lifshitz theory of the longitudinal spin Seebeck effect

“…To this end, spin waves in the ferrimagnetic insulator yttrium iron garnet (YIG) appear particularly promising as they suffer from a remarkably low Gilbert damping (at microwave frequencies), α ∼ 10 −4 , and the host material has Curie temperature of ∼ 500 K, thus remaining magnetic at room temperature. 14 Spin waves in YIG have recently been shown to undergo roomtemperature Bose-Einstein condensation under nonlinear microwave pumping, 15 exhibit large spin pumping into adjacent conductors, [16][17][18] manifest the longitudinal spin Seebeck effect, 19 and efficiently move domain walls under small thermal gradients. 11 These phenomena hold promise for integrated circuits based on nonvolatile magnetic elements 20 with essentially no Ohmic losses and thus very low dissipation.…”

Electronic Pumping of Quasiequilibrium Bose-Einstein-Condensed Magnons

“…Considering that the classically unstable region (∆µ > gs ) has already been realized in practice [11] in a Pt/YIG bilayer spin-biased by the inverse spin Hall effect, and the spin-caloritronic properties [12] are presently under intense experimental scrutiny in such composites [10,17], the experimental observation of current-induced BEC phase in Pt/YIG hybrids appears very feasible. YIG film thickness larger than the characteristic de Broglie wavelength of magnons (∼ 1 nm at room temperature using standard YIG parameters [18]) would justify a threedimensional treatment of BEC. A d L 1 µm-thick YIG film with Gilbert damping α 10 −4 like that employed in Ref.…”