Mixed spectral statistics in ferrite-loaded microwave billiards

We investigate mixed spectral statistics in magnetized ferrite-loaded microwave billiards by resolving the spectrum with respect to the longitudinal quantum number k_z. Different longitudinal mode families exhibit distinct random-matrix statistics, leading to the coexistence of Poisson-, GOE-, and GUE-like subspectra in different geometries and frequency regimes. Within the same frequency window, these mode families coexist, giving rise to a complete spectrum that cannot be described by a single random-matrix ensemble. Based on the actual modal composition, we construct mixed random-matrix models as superpositions of statistically independent subspectra. The models reproduce both short-range and long-range spectral correlations without additional fitting parameters. These results show that the mixed spectral statistics is governed by the weighted coexistence of symmetry-distinguished mode families, rather than by a continuous crossover within a single ensemble.