Two-dimensional transition metal dichalcogenides (TMDs) have been attracting significant interest 1-8 due to a range of properties, such as layer-dependent inversion symmetry, valleycontrasted Berry curvatures, and strong spin-orbit coupling (SOC). Of particular interest is niobium diselenide (NbSe 2 ), whose superconducting state in few-layer samples is profoundly affected by an unusual type of SOC called Ising SOC 7 . Combined with the reduced dimensionality, the latter stabilizes the superconducting state against magnetic fields up to ~35 T and could lead to other exotic properties such as nodal and crystalline topological superconductivity 9-14 . Here, we report transport measurements of few-layer NbSe 2 under inplane external magnetic fields, revealing an unexpected two-fold rotational symmetry of the superconducting state. In contrast to the three-fold symmetry of the lattice, we observe that

We have performed a comprehensive study and developed a semi-analytical model of the transient behavior of three-magnon scattering of ferromagnetic resonance. For powers above the Suhl instability, we observe a secondary nonlinear regime in which the resonance amplitude oscillates while relaxing to its steady-state value. This behavior is in both qualitative and quantitative agreement with our model despite the onset of higher-order interactions. As the power increases, the oscillations lead to 180 • phase shifts in the resonance, which results in switching between three-magnon splitting and confluence. These findings deepen the understanding of the transient behavior and directionality of three-magnon scattering.