Brillouin light scattering from quantized spin waves in nanowires with antisymmetric exchange interactions

Antisymmetric exchange interactions lead to non-reciprocal spin-wave propagation. As a result, spin waves confined in nanostructure are not standing waves; they have time-dependent phase, because counter-propagating of the same frequency different wavelengths. We report on Brillouin light scattering (BLS) study Co/Pt nanowires with strong Dzyaloshinskii-Moriya (DMI). Spin-wave quantization narrow ($\lesssim 200$ nm width) wires dramatically reduces shift between BLS Stokes and anti-Stokes lines associated incident transverse nanowires. In contrast, propagating along nanowire length is independent width. A model that considers chiral nature modes captures this physics predicts dramatic reduction scattered from higher energy wires, which confirmed by our experiments.