Seminars Archive

Transient Grating generation of magnetoelastic waves

Abstract
Control of material properties is one of the driving forces in ultrafast optical sciences. The notion that light can influence intrinsic material parameters is founded on a wide range of experiments demonstrating opto-magnetic control, light induced superconductivity, and the photo induced insulator to metal transition in a wide range of materials. A recent addition to the tool chest of control methodologies is the excitation of acoustic waves, and their affect on intrinsic materials properties; particularly the material magnetization via magnetostrictive effects. In this talk I will describe our recent results [1] where we generate magneto elastic waves in the test material nickel. Using a combination of the transient grating and Faraday techniques, we probe the magnetic components of the intrinsically acoustic excitations generated in the TG geometry. The dispersion characteristics of our excitations can be uniquely identified as arising from Rayleigh and Longitudinal acoustic excitations. At particular values of applied external magnetic field, the acoustic excitation couples to a k-vector tunable ferromagnetic resonance in the film. I will also discuss the potential for implementing such measurements on FEL sources with emphasis paid to recent results from Fermi [2]. The magnetoelastic response provides a facile manner by which to probe ever-decreasing TG spatial periods without the otherwise necessary reduction in probe wavelength. [1] J. Janusonis et.al. APL 106, 181601 (2015). [2] F. Bencivenga et.al Nature 520, 205 (2015).