  We consider the magnonic properties of two dipolarly coupled magnetic
stripes, both deposited on a normal conductive substrate with strong spin-orbit
coupling. A charge current in the substrate acts on the adjacent magnets with
spin-orbit torques, which result in magnonic damping or antidamping of the spin
waves, and hence a gain-loss coupling of the two magnetic stripes. The whole
setup is demonstrated to exhibit features typical for parity-time (PT)
symmetric systems. Phenomena are demonstrated that can be functionalized in
magnonic devices, including reconfigurable magnonic diodes and logic devices.
Alternative stripes designs and PT-symmetric, periodic, coupled magnonic
textures are studied. Analytical and full numerical analysis identify the
conditions for the appearance of exceptional points (EPs), where magnonic gain
and loss are balanced and evidence nonreciprocal magnon propagation and
enhanced magnon excitation around EPs. Furthermore, the dipolar coupling is
shown to bring in a wave vector-dependent PT-symmetric behavior. Proposing and
simulating a PT-symmetric magnonic crystal, we show how EPs and hence
associated phenomena can be steered to a particular wave vector in a gaped
spectrum via material design. The phenomena offer additional tools for
magnonic-based communication and computational devices.
