Abnormal Magnetic Phase Transition in FeRh Films on Al₂O₃ via Anomalous Nernst Effect

Iron rhodium (FeRh) undergoes a first-order antiferromagnetic to ferromagnetic phase transition above its Curie temperature. In (110)-oriented FeRh films on Al₂O₃ substrates, the anomalous Nernst effect (ANE) thermopower was measured over 100–350 K, revealing consistent magnetic transport behaviors for both in-plane (IM) and out-of-plane (PM) magnetization configurations. The ANE voltage was found proportional to the material's magnetization, with a notable sign reversal near zero field at low temperatures due to the diamagnetic Al₂O₃ substrate. Simulations using the Heisenberg spin model and Landau–Lifshitz–Gilbert equation confirmed abnormal heat transport behavior from the substrate during the phase transition. These findings suggest FeRh films on Al₂O₃ substrates have unique potential for spintronics applications, neuromorphic computing, and magnetic memory devices.