Depth-resolved distribution of ultrafast spin currents and fluctuation in magnetic structures
Final Report Abstract
Chiral magnetic structures, such as spin spirals, chiral domain walls and skyrmions, have been intensively studied due to their intriguing properties, such as potentially enhanced stability and efficient spin-orbit torque-driven dynamics. These structures are stabilized by the Dzyaloshinskii-Moriya interaction (DMI), which favors a chiral winding of the magnetization. A key step of this experimental work is the comparison of the collinear ferromagnetic order dynamics and the chiral order dynamics. To explain the key finding of the experimentally observed faster recovery of the chiral signal after laser excitation we envisage two different mechanisms: (i) a change in the size ratio between domain walls and domains caused by an increase of the domain wall width during the whole investigated time frame or (ii) a faster recovery dynamic of the chiral order within the domain walls compared to the ferromagnetic order in the domains leading to a faster build-up of the chiral magnetization. Our study paves the way for future investigations of fundamental aspects such as the dependence of the timescales of the chiral order build-up on the absolute strength of the DMI by varying the heavy metal layers. The control of the DMI and the chirality of the spin structures on the ultrafast timescale may ultimately allow the controlled ultrafast manipulation of chiral magnetism, e.g. the ultrafast writing of chiral topological objects such as skyrmions, and pave the way for applications in the field of ultrafast chiral spintronics. The scientific groups from France, Germany, Italy, and the USA participated in these studies. The exchange of experience and the use of the scientific potential of these groups made it possible to obtain these results. The creation of nanoscale periodic gratings on metallic multilayer structures opens up a number of new scientific directions related to both magnetism (e.g., the creation and control of skyrmions) and plasma physics on the temporal interval order of 50-60 femtoseconds (in our case, self-diffraction and the generation of electron-hole pairs) and solid-state physics (coherent magnons and phonons). This greatly expands the possibilities of the FEL and leads to the development of new research methods. The possibility of creating magnetic transient gratings with a period of less than 50 nm is mentioned in reviews on FEL as one of the research methods.
Publications
-
Faster chiral versus collinear magnetic order recovery after optical excitation revealed by femtosecond XUV scattering. Nature Communications, 11(1).
Kerber, Nico; Ksenzov, Dmitriy; Freimuth, Frank; Capotondi, Flavio; Pedersoli, Emanuele; Lopez-Quintas, Ignacio; Seng, Boris; Cramer, Joel; Litzius, Kai; Lacour, Daniel; Zabel, Hartmut; Mokrousov, Yuriy; Kläui, Mathias & Gutt, Christian
-
Nanoscale Transient Magnetization Gratings Created and Probed by Femtosecond Extreme Ultraviolet Pulses. Nano Letters, 21(7), 2905-2911.
Ksenzov, Dmitriy; Maznev, Alexei A.; Unikandanunni, Vivek; Bencivenga, Filippo; Capotondi, Flavio; Caretta, Antonio; Foglia, Laura; Malvestuto, Marco; Masciovecchio, Claudio; Mincigrucci, Riccardo; Nelson, Keith A.; Pancaldi, Matteo; Pedersoli, Emanuele; Randolph, Lisa; Rahmann, Hendrik; Urazhdin, Sergei; Bonetti, Stefano & Gutt, Christian
-
MHz-Rate Ultrafast X-ray scattering and holographic imaging at the European XFEL ournal of Synchrotron Radiation 29, 1454 (2022)
N.Z. Hagström et al.
