  Active manipulation of spin waves is essential for the development of
magnon-based technologies. Here, we demonstrate programmable spin-wave
filtering by resetting the spin structure of a pinned 90$^\circ$ N\'{e}el
domain wall in a continuous CoFeB film with abrupt rotations of uniaxial
magnetic anisotropy. Using phase-resolved micro-focused Brillouin light
scattering and micromagnetic simulations, we show that broad 90$^\circ$
head-to-head or tail-to-tail magnetic domain walls are transparent to spin
waves over a broad frequency range. In contrast, magnetic switching to a
90$^\circ$ head-to-tail configuration produces much narrower domain walls at
the same pinning locations. Spin waves are strongly reflected by a resonance
mode in these magnetic domain walls. Based on these results, we propose a
magnetic spin-wave valve with two parallel domain walls. Switching the
spin-wave valve from an open to a close state changes the transmission of spin
waves from nearly 100% to 0% at the resonance frequency. This active control
over spin-wave transport could be utilized in magnonic logic devices or
non-volatile memory elements.
