Evolution of chiral magnetic domain walls

The chirality of Néel magnetic domain walls can be measured by x-ray circular dichroism in resonant magnetic scattering. Their ultrafast evolution is explained as an increase of the walls width and a reduction of the magnetization, due to a spin current of hot electrons passing from the domain through the domain walls.

Léveillé et al., Nature Communications, Vol. 13 - 1, pp. 1412 (2022).
 

Ultrafast evolution of chiral domain walls

The system is pumped by an infrared femtosecond pump pulse and it's ultrafast dynamics are measured through the magnetic scattering of left (CL) and right (CR) circularly polarized FEL pulses.

The asymmetry ratio (CL-CR)/(CL+CR) maps the relation between the magnetization of domain walls and cores. A 15% dip in the asymmetry in the first ps of the dynamics shows a faster demagnetization of the walls, explained as a spin current generating opposite torques on the sides of the domain walls producing a transient tilting of the wall magnetization out of the Néel plane.

Such a mixed Bloch/Néel/Bloch contribution in the domain wall reduces the effective chirality, building opposite transient Bloch components on domain walls sides of the initially pure Néel wall structure, imposed by the Dzyaloshinskii–Moriya interaction.

After a few ps, the domain walls recover their initial chiral Néel configuration preserving the original sense of rotation together with a recovery of their magnetization.

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

C. Léveillé, E. Burgos-Parra, Y.Sassi, F. Ajejas, V. Chardonnet, E. Pedersoli, F. Capotondi, G. De Ninno, F. Maccherozzi, S. Dhesi, D.M. Burn, G. van der Laan, O.S. Latcham, A.V. Shytov, V.V. Kruglyak, E. Jal, V. Cros, J.Y. Chauleau, N. Reyren, M. Viret, N. Jaouen

Nature Communications, Vol. 13 - 1, pp. 1412 (2022).

DOI: 10.1038/s41467-022-28899-0

Last Updated on Thursday, 24 March 2022 16:30