Impact of optimized growth conditions for magnetic phase transition and magnetic domain evolution in epitaxial FeRh thin films

FeRh undergoes a first-order magnetic phase transition, transitioning from a low-temperature antiferromagnetic state to a high-temperature ferromagnetic state around 370 K. This magnetic phase transition is profoundly affected by external parameters, such as composition and strain, which can be precisely controlled by varying growth conditions. Here, we present an investigation of FeRh thin films grown under various conditions, including annealing time and sputtering gun power. FeRh film grown at the optimal conditions yields a sharp and steep transition behavior, with maximal magnetization change between the antiferromagnetic and ferromagnetic phases. Magnetic force microscopy reveals that the optimal film displays directional domain growth, aligned with the crystallographic direction, while the non-optimal film shows random domain nucleation. Furthermore, we observe that the optimal film exhibits no significant correlation between surface morphology and magnetic domains, in contrast to the non-optimal film, where the surface morphology and magnetic domains are closely correlated. Our results highlight the critical interplay between growth conditions and film quality, emphasizing the importance of film optimization in the study of FeRh's magnetic phase transition. This comprehensive investigation provides valuable insights into the magnetic properties of FeRh, paving the way for future technological applications.