Non-local spin transport via sustained noncollinear textures in ferromagnetic nanowires

Long-range, dynamic noncollinear textures [1] can be sustained in ferromagnetic nanowires by the non-local compensation of damping [2]. In contrast to current-driven magnons, noncollinear textures exhibit (1) frequencies under ferromagnetic resonance that are inversely proportional to damping; (2) an excitation threshold that is proportional to the in-plane anisotropy; and (3) coherence over the length of the nanowire. We analytically demonstrate that nonlinearities are fundamental to describe these characteristics. Two generic solutions when the nanowire is subject to spin injection at one edge are found, exhibiting opposite frequency tunabilities. This is in stark contrast to the linear frequency tunability predicted for spin superfluids. By micromagnetic simulations, we show that these predictions hold in the presence of in-plane anisotropy and non-local dipole fields.
References
[1] Iacocca et al., Phys. Rev. Lett. 118, 017203 (2017)
[2] König et al., Phys. Rev. Lett. 87, 187202 (2010); Sonin Adv. Phys. 59, 181 (2010); Takei and Tserkovnyak, Phys. Rev. Lett. 112, 227201 (2014)
[2] Iacocca et al., Phys. Rev. B 96, 134434 (2017)