Magnetization Dynamics in Magnetic Nanostructures

Abstract

Using a time-resolved “pump-probe” technique, we have studied the magnetization dynamics in magnetic thin films with a time resolution of about 20ps. As pump we used the high-frequency magnetic fields induced by voltage pulses applied on a 50Ω-matched coplanar wave-guide. As probe we used the Magneto-Optical Kerr effect and Magneto- Resistive effect. We present the wave-guide and device preparation realized by UV lithography, sputtering and various etching techniques. The magnetization dynamics results concern both small angle perturbations, such as Ferromagnetic Resonance, and large angle perturbations such as the magnetization reversal. For the latter case, we have evidenced the magnetization reversal by precession, in micron-sized spin-valve elements and continuous magnetic films. This process, known as the fastest magnetization reversal process, has direct applications in Magnetic Random Access Memories (MRAM) devices.