Large nonlinear ferromagnetic resonance shift and strong magnon-magnon coupling in Ni80Fe20 nanocross array

We report microwave-power-driven strong magnon-magnon coupling in $\mathrm{N}{\mathrm{i}}_{80}\mathrm{F}{\mathrm{e}}_{20}$ nanocross array with large anticrossing gaps up to 1.03 GHz. We also observe microwave-driven large nonlinear shift in ferromagnetic resonance (FMR) frequency with its sign dependent on the strength of bias magnetic field. A drastic enhancement of inter-nanocross-dynamic dipolar interaction results in the anticrossing, while variation in internal spin texture leads to the nonlinear FMR shift. The tunable coupling strength and nonlinearity by microwave power ushers externally controlled nonlinear magnonic devices.