  Rectification phenomenon caused by the simultaneous breaking of time reversal
and spatial inversion symmetries has been extended to a wide range of
(quasi)particles and waves; however, the nonreciprocal diffraction, which is
the imbalance of upward and downward deflections, was previously observed only
for photons and remained to be extended to other (quasi)particles. In this
study, we present evidence of the nonreciprocal diffraction of surface acoustic
wave (SAW) utilizing a magnetoelastic grating on a SAW device. Asymmetric
diffraction intensities were observed when the ferromagnetic resonance was
acoustically excited. Based on a theoretical model, we attribute the
microscopic origin of this phenomenon to the resonant scattering involving
ferromagnetic resonance excitations. The novel property may pave an avenue to
further development of SAW devices for various purposes, including microwave
communications and quantum engineering applications.
