Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 40: Focus: Terahertz radiation and magnetism

MA 40.4: Hauptvortrag

Donnerstag, 10. März 2016, 11:15–11:45, H32

Precessional spin motion and magnetization quenching induced by intense Terahertz pulses — •Christoph Hauri — SwissFEL, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland

Laser pulses in the low-frequency Terahertz range (1−15 THz) with field strength up to several GV/m and several Tesla have become available only very recently. Such pulses offer novel opportunities to explore ultrafast magnetization dynamics and magnetic domain switching in a regime differing from the commonly used optical lasers where the magnetization control is mediated by heat deposition. We show that strong THz fields allow coherent spin excitation even without exciting a magnetic mode (e.g., magnon). Our investigations on cobalt, nickel and iron thin films unravel the onset of a co-existence of precessional motion and ultrafast magnetization quenching as function of the THz field strength. While the coherent precessional motion is induced by the magnetic field the concomitant electric field component gives rise to fast demagnetization. Our findings illustrate the fundamental limits of metallic ferromagnetic thin films in view of magnetic switching by THz fields.