Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 70: Symposium Photons in Magnetism (SYPM, jointly with MA, HL, MI)

O 70.1: Hauptvortrag

Donnerstag, 14. März 2013, 15:00–15:30, H1

Ultrafast emergence of nanoscale ferromagnetism far from equilibrium — •Hermann Dürr — SLAC National Accelerator Laboratory, Menlo Park USA

Long-range magnetic order in solids is usually ascribed to the exchange interaction between electron spins. Close to equilibrium this leads to spontaneous magnetization when the system cools below the magnetic ordering temperature. We show that the far from equilibrium flow of angular momentum via spin currents can also achieve long-range ferromagnetic order even above the ordering temperature. To reveal this process, we use ultrafast x-ray diffraction at SLAC's Linac Coherent Light Source to probe the nucleation, growth and transient existence of ferromagnetic order on the nm length and fs timescale after fs optical laser excitation has brought a metallic 3d - 4f alloy system into a highly non-equilibrium chaotic spin state. The technological exploitation of this effect could pave the way for novel ways to manipulate and transport information within the smallest space-time dimensions.