Our paper on Barkhausen noise from domain wall motion in the precessional regime has been published in Physical Review Letters. In this paper, we study the role of the dynamical internal structure of domain walls on their bursty dynamics in disordered ferromagnetic thin films. The phenomenon of jerky domain wall motion in disordered ferromagnets is known as Barkhausen noise, and constitutes an important example of the more general phenomenon of “crackling noise” found in a large class of driven systems. In the precessional regime we study here, the domain walls contain topologically stable textures known as Bloch lines which repeatedly nucleate, propagate and annihilate within the domain wall during its motion. We show that also this internal dynamics within the domain wall exhibits crackling noise similarly to the domain wall propagation, with the magnitude of the internal dynamics actually exceeding that related to domain wall displacement. This finding provides a novel angle to the well-studied phenomenon of Barkhausen noise, highlighting the importance of the internal degrees of freedom of the domain walls neglected in the past.
Touko Herranen and Lasse Laurson, Barkhausen noise from precessional domain wall motion, Phys. Rev. Lett. 112, 117205 (2019).
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