Anomalies in the dynamics of ferrimagnets near the angular momentum compensation point

•Model of ferrimagnet dynamics near angular momentum compensation point (TA) is elaborated.•Post Walker domain wall regime close to TA is explored.•Anomalies of dynamic quantities in the vicinity of TA are revealed. In this paper, we elaborate analytical theory of domain wall dynamics close to the angular momentum compensation point based on non-linear dynamic equations derived from the effective Lagrangian of a ferrimagnet. In the framework of the proposed model, we explore dynamic processes in the Walker and post-Walker regimes. Analysis of the precession angle and domain wall’s velocity oscillations in post-Walker regime in a ferrimagnet is performed. We show that although spin oscillations quench the dynamics of domain walls near the Walker breakdown field, a further increase of the driving magnetic field increases domain wall speed and mobility. An anomalous behavior of domain wall dynamic properties near the angular momentum compensation point in ferrimagnets (unlimited enhancement of the domain velocity, vanishing of effective dynamic mass) is discussed.