Ultrafast time-evolution of chiral Néel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering

Cyril Léveillé, Erick Burgos-Parra, Yanis Sassi, Fernando Ajejas, Valentin Chardonnet, Emanuele Pedersoli, Flavio Capotondi, Giovanni De Ninno, Francesco Maccherozzi, Sarnjeet Dhesi, David M. Burn, Gerrit van der Laan, Oliver S. Latcham, Andrey V. Shytov, Volodymyr V. Kruglyak, Emmanuelle Jal, Vincent Cros, Jean-Yves Chauleau, Nicolas Reyren, Michel Viret & Nicolas Jaouen

Nature Communications volume 13, Article number: 1412 (2022),Ultrafast time-evolution of chiral Néel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering | Nature Communications ,Cite this article

Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows for the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions among others. We report here on the behavior of chiral DWs at ultrashort timescale after optical pumping in perpendicularly magnetized asymmetric multilayers. The magnetization dynamics is probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously varying spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of spins from the interior of the neighboring magnetic domains. We identify this time-varying change of the DW texture shortly after the laser pulse as a distortion of the homochiral Néel shape toward a transient mixed Bloch-Néel-Bloch texture along a direction transverse to the DW.

Nature Communications volume 13, Article number: 1412 (2022),Ultrafast time-evolution of chiral Néel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering | Nature Communications ,Cite this article