  One of the most fundamental forms of magnon-phonon interaction is an
intrinsic property of magnetic materials, the "magnetoelastic coupling". This
particular form of interaction has been the basis for describing magnetic
materials and their strain related applications, where strain induces changes
of internal magnetic fields. Different from the magnetoelastic coupling, more
than 40 years ago, it was proposed that surface acoustic waves may induce
surface magnons via rotational motion of the lattice in anisotropic magnets.
However, a signature of this magnon-phonon coupling mechanism, termed
magneto-rotation coupling, has been elusive. Here, we report the first
observation and theoretical framework of the magneto-rotation coupling in a
perpendicularly anisotropic ultra-thin film Ta/CoFeB(1.6 nm)/MgO, which
consequently induces nonreciprocal acoustic wave attenuation with a
unprecedented ratio up to 100$\%$ rectification at the theoretically predicted
optimized condition. Our work not only experimentally demonstrates a
fundamentally new path for investigating magnon-phonon coupling, but also
justify the feasibility of the magneto-rotation coupling based application.
