  Hybrid magnonic systems host a variety of characteristic quantum phenomena
such as the magnetically-induced transparency (MIT) and Purcell effect, which
are considered useful for future coherent quantum information processing. In
this work, we experimentally demonstrate a tunable MIT effect in the
Y3Fe5O12(YIG)/Permalloy(Py) magnon-magnon coupled system via changing the
magnetic field orientations. By probing the magneto-optic effects of Py and
YIG, we identify clear features of MIT spectra induced by the mode
hybridization between the uniform mode of Py and the perpendicular standing
spin-wave modes of YIG. By changing the external magnetic field orientations,
we observe a tunable coupling strength between the YIG's spin-wave modes and
the Py's uniform mode, upon the application of an out-of-plane magnetic field.
This observation is theoretically interpreted by a geometrical consideration of
the Py and YIG magnetization under the oblique magnetic field even at a
constant interfacial exchange coupling. Our findings show high promise for
investigating tunable coherent phenomena with hybrid magnonic platforms.
