Static properties and current-induced magnetization dynamics of pinned 90° domain wall

When a thin ferromagnetic layer is placed on a ferroelectric one, a modulation of magnetic anisotropy can be induced by magnetoelectric coupling between the layers. Namely, ferroelectric domain pattern is imprinted into the ferromagnet and local uniaxial magnetic anisotropy in the ferromagnetic layer rotates between the domains by 90° [1]. As a result, 90° magnetic domain walls are formed at the anisotropy boundaries. Using spin transfer torque effect from an AC spin polarized current, it is possible to drive the pinned magnetic domain wall into high frequency oscillations, which can be used as a tunable source of spin waves [2]. Motivated by a better understanding of static and dynamic properties of the 90° magnetic domain walls, we provide a theoretical study based on 1D analytical model [3]. In accord with micromagnetic simulations, the model predicts active tuning of the domain wall eigenfrequency by a magnetic bias field.

[1] T. H. E. Lahtinen, J. O. Tuomi, and S. van Dijken, Adv. Mat. 23, 3187 (2011).
[2] B. Van de Wiele, S. J. Hämäläinen, P. Baláž, F. Montoncello, and S. van Dijken, Sci. Rep. 6, 21330 (2016).
[3] P. Baláž, S. J. Hämäläinen, and S. van Dijken, Phys. Rev. B 98, 064417 (2018).