Robustness and tunability of spin dynamics in FeRh films under magnetic inhomogeneity control

Understanding and controlling spin precession dynamics are crucial for ultrafast magnetic switching in spintronic devices and next-generation memory technologies. In this work, we investigate how the coherent spin precession in the ferromagnetic state of FeRh is influenced by various types of spatial magnetic inhomogeneity, including a deficiency of ferromagnetic ions and two- or three-dimensional mixtures of ferromagnetic (FM) and antiferromagnetic (AFM) phases. H+-ion irradiation is widely used to stabilize the FM state of FeRh at room temperature, and our results reveal that it has little effect on the main characteristics of spin precession dynamics. In the coexisting FM–AFM phases, we found that FM resonance is strongly influenced by exchange interactions across the magnetic phase boundaries, resulting in significant changes in the precessional frequency and the damping coefficient. These findings highlight both the robustness and the tunability of spin dynamics using the material design and the magnetic phase control, which can be useful for spintronic applications.