Generation of spin waves via spin-phonon interaction in a buried dielectric thin film

Abstract

In this paper, we investigate the magnetic, optical, and lattice responses of a Pt/Cu/Bi 1 Y 2 Fe 5 O 12 /Gd 3 Ga 5 O 12 heterostructure to femtosecond laser excitation of the opaque Pt/Cu metallic bilayer. The electronic excitation generates coherent and incoherent phonons, which trigger high-frequency standing spin waves (SWs) in the dielectric Bi 1 Y 2 Fe 5 O 12 layer via a phonon-induced change of magnetic anisotropy. We find that the incoherent phonons (heat) can induce a fast (<1ps) and slow (>1000 ps) decrease of the magnetic order by different spin-phonon interaction scenarios. These results open perspectives for generating high-frequency SWs in buried magnetic garnets.

Enhancement of ultrafast demagnetization rate and Gilbert damping driven by femtosecond laser-induced spin currents in Fe81Ga19/IZhang1, Liu2, Yuan3 et al. 2019Phys. Rev. B

“…According to Ref. 45, the oscillations amplitude of acoustic mode increases linearly with the laser energy density within the probed range. Moreover, the FeGa material with a thickness as thick as 60 nm is preferred to induce an obvious magnetoelastic behavior [46], while 10 nm at the present experiment is probably too thin.…”

“…Besides, FeGa alloys are particularly interesting because of their magneto-elastic properties [44]. The acoustic waves are possible to be triggered by ultrashort laser and as a result, spin precession would be excited non-thermally via a magnetoelastic effect [45]. However, this effect can be excluded based on the following reasons: firstly, the external field has to be applied along with the hard axis of FeGa, otherwise, the magnetization precession cannot be induced.…”

Giant widening of interface magnetic layer in almost compensated iron garnet

“…Since quantities of ions in the sublattices are in the ratio of 2 : 3 and an interaction between the sublattices is AFM, the magnetic structure turns out to be ferrimagnetic. Prominent magneto-optical characteristics [7] and extremely weak damping of spin waves [8] make IG the basis of various optoelectronic and promising spin-wave devices development [7,9,10].…”

Ultrafast control of lattice strain via magnetic circular dichroism

“…So far, this approach has attracted attention in two different ways: The first is related to controlling the magnetization dynamics with picosecond strain pulses generated in metallic film by femtosecond laser pulses [29][30][31][32][33]. It was demonstrated that a strain pulse can trigger a coherent magnetization precession in metal [29][30][31], semiconductor [32], and dielectric [33,34] magnetic films. Because of its long propagation distance of several millimeters combined with low energy losses [35,36], strain pulses offer an important opportunity to excite magnetization precession in magnetic materials deeply embedded in opaque heterostructure devices [32][33][34].…”

“…It was demonstrated that a strain pulse can trigger a coherent magnetization precession in metal [29][30][31], semiconductor [32], and dielectric [33,34] magnetic films. Because of its long propagation distance of several millimeters combined with low energy losses [35,36], strain pulses offer an important opportunity to excite magnetization precession in magnetic materials deeply embedded in opaque heterostructure devices [32][33][34]. The second way is related to control the lattice strain by the ultrafast modification of the magnetic order [14,23,[37][38][39][40][41].…”