Gilbert damping control with non-collinear dual optical excitation

We investigate the impact of non-collinear dual optical excitation on magnetization precession in a permalloy thin film using two ultrashort laser pulses. By analyzing the magnetization dynamics using time-resolved magneto-optical methods, we find that excitation with two ultrashort optical pulses introduces long-lasting modification of the electron system seen as a significant increase (about a factor of 2 more) in magnetic damping. Our results reveal that the observed effect strongly depends on the respective polarization of the two excitation pulses and the time delay between them. Our findings may indicate the occurrence of a new physical effect during photoexcitation with two non-collinear optical pulses, which can potentially be observed in various materials and with photon excitations at different energies.