Magnons and acoustic phonons inY3−xBixFe

Damping of Standing Spin Waves in Bismuth-Substituted Yttrium Iron Garnet as Seen via the Time-Resolved Magneto-Optical Kerr Effect

“…2(c)]. We obtain an exchange stiffness of D ex = (5.9 ± 0.2) 10 −17 T m 2 , which is in good agreement with those reported in the literature for YIG and Bi-YIG [45][46][47]. This clearly demonstrates the SSW nature of the observed magnetic resonances modes.…”

Measurement of transient strain induced by two-photon excitation

“…3(a). Here, we used a film thickness of d = 135 nm, the linear absorption coefficient for NUV light α = 6 × 10 4 cm −1 , the elastic constant C 11 = 190 GPa for Bi 2 Y 1 Fe 5 O 12 , and the Grüneisen parameter of YIG, ≈ 1, reported in the literature [26,40,51,57]. The lattice strain η generated via nonlinear NIR absorption can also be calculated in the same manner with a different value of C 11 = 230 GPa for Bi 1 Y 2 Fe 5 O 12 ,…”

“…The maximum at 25 ps in Fig. 2(b) is slightly delayed, because the higher sound velocity v 1 = 6.3 nm/ps for x = 1 as compared to v 2 = 5.4 nm/ps for x = 2 [40,51] is overcompensated by the layer thickness d. Second, the subsequent falling edge shows an almost linear strain decrease from 25 to 50 ps for NIR excitation, whereas for NUV excitation the slope shows an exponential-like decrease. This is observed for both samples and is due to the nearly homogeneous nonlinear absorption in contrast to the steeper intensity profile for linear absorption, displayed in Fig.…”

“…The larger speed of sound is partially compensated by the increased layer thicknesses such that we qualitatively find the same transient response to laser excitation. The increased lattice constant upon doping [40] does not affect our results as we examine solely the relative changes of the lattice. Thus the two samples allow us to crosscheck the amplitudes and timings of the photoinduced strain transients.…”

Laser-Induced Spatiotemporal Dynamics of Magnetic Films

“…Strictly speaking, the damping of phonons and magnon are not necessarily independent, since magnetization is affected by phonon attenuation via the MEC [27]. We treat Gilbert damping constant α and phonon relaxation time τ p as independent parameters since Gilbert damping can also be caused by magnetic disorder, surface roughness or defects [28]. We define the anisotropic spin wave frequency Ω 0 = γµ 0 H(H + M 0 sin 2 θ) and the MEC frequency parameter ∆(k) = γb 2 k 2 /(4M 0 ρΩ 0 ) with θ being the angle between magnetic field and in-plane wave vector k. The spatiotemporal dynamics of Φ(r, t) reads…”