Spin waves in magnetic insulators

In this talk, I will present our theoretical work on the spin wave dynamics in magnetic insulators. I will analyze recent experimental observations generated by an ultrafast focused laser pulse, where we find that the spin wave excitation is dominated by the acoustic-wave-mediated mechanism. In our theory, we take into account both volume and surface spin wave modes in the presence of applied, dipolar and magnetic anisotropy fields and include the dependence on laser spot exposure size and magnetic damping. In the second part of this talk, I will discuss the spin wave modes in YIG and GdIG calculated from the atomistic model, which may help to understand various experiments such as spin Seebeck effect and ferromagnetic resonance. The temperature dependence of the spin wave spectrum is obtained from a mean field approximation in the presence of thermal excitation.