MBI Colloquium

Mittwoch, 08. Januar 2025 // 14.00 -

Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie

Max-Born-Straße 2a, 12489 Berlin
Max Born Hall

Applications of all-optical switching of magnetization: Photonic memory, magnetic sensors and writing skyrmions

Prof. Bert Koopmans

Department of Applied Physics, Eindhoven Hendrik Casimir Institute, Eindhoven University of Technology

Novel schemes for controlling the ferromagnetic state at femtosecond time scales by pulsed laser excitation have received great interest. By driving systems into the strongly non-equilibrium regime, it has been shown possible not only to quench magnetic order, but also to switch the magnetization by single laser pulses – so-called all-optical switching (AOS). In parallel, it has been found that pulsed laser excitation can also induce spin currents over several to tens of nanometers, which can act as an additional source of sub-picosecond magnetization dynamics. Thereby, a scientifically exciting link between the fields of ‘femtomagnetism’ and spintronic transport physics has emerged. Moreover, it is being envisioned that combining the two fields could pave the way to a new class of hybrid spintronic-photonic devices, in which data is copied between photonic and magnetic (spintronic) domain without any intermediate electronic steps, leading to ultrafast and highly energy-efficient IT solutions.

In this Colloquium, the underlying phenomena will be introduced, and a selection of experimental results will be presented. Simple models will be explained that provide an intuitive feeling of the various phenomena involved and their interplay. After this introduction, some of our recent experiments on applications of AOS will be presented. First, I will discuss recent progress towards realizing integrated spintronic-photonic memory, by demonstrating on-chip magneto-optical reading and on-chip AOS. Then I will address experiments on optically switching of the ‘exchange bias’ effect, which could be used for reprogrammable magnetic field sensors. Finally, I will report on our first attempts of fieldfree all-optical creation and annihilation of skyrmionic textures by single femtosecond laser pulses.