Recent Advances in the Understanding of Dynamic Phase Transitions in Ferromagnetic Thin Films*

The magnetization dynamics of ferromagnetic thin films can exhibit abrupt changes in its trajectory if one alters the period P or amplitude H₀ of the dynamics generating external magnetic field. Such changes impact the period averaged magnetization vector Q, which is the dynamic order parameter, and its behavior can be explored by means of non-equilibrium phase diagrams. The fundamental behavior of Q exhibits significant similarities with the equilibrium phase properties of ferromagnets, which makes its understanding crucially relevant in the field of non-equilibrium physics [1]. Only recent progress in magneto-optical Kerr effect detection have allowed for detailed experimental explorations of the complete dynamic phase space. Here, we present some of our most recent experimental results, specifically related to our studies of the vector nature of Q in thin films with uniaxial anisotropy, as well as work on the general definition of the conjugate field of Q.
[1] P. Riego, P. Vavassori, A. Berger, Physica B 549, 13 (2018)