  We report the experimental demonstration of an abnormal, opposite
anti-crossing effect in a photon-magnon-coupled system that consists of an
Yttrium Iron Garnet film and an inverted pattern of split-ring resonator
structure (noted as ISRR) in a planar geometry. It is found that the normal
shape of anti-crossing dispersion typically observed in photon-magnon coupling
is changed to its opposite anti-crossing shape just by changing the
position/orientation of the ISRR's split gap with respect to the microstrip
line axis along which ac microwave currents are applied. Characteristic
features of the opposite anti-crossing dispersion and its linewidth evolution
are analyzed with the help of analytical derivations based on electromagnetic
interactions. The observed opposite anti-crossing dispersion is ascribed to the
compensation of both intrinsic damping and coupling-induced damping in the
magnon modes. This compensation is achievable by controlling the relative
strength and phase of oscillating magnetic fields generated from the ISRR's
split gap and the microstrip feeding line. The position/orientation of an
ISRR's split gap provides a robust means of controlling the dispersion shape of
anti-crossing and its damping in a photon-magnon coupling, thereby offering
more opportunity for advanced designs of microwave devices.
