Robust Anomalous Hall Effect in Polycrystalline FeRh Thin Film During Ferromagnetic-Antiferromagnetic Phase Transition

Research on antiferromagnets and ferromagnets is actively progressing, focusing on the antisymmetric properties of ferromagnets and the proximity effect between ferromagnet and heavy metal layers. Antiferromagnets are notable for their high-speed operating frequency (THz) and vanishing field characteristics, and both materials exhibit anomalous optical and transport phenomena. FeRh, which exhibits temperature-dependent ferromagnetic (FM), ferromagnetic-antiferromagnetic metastable, and antiferromagnetic (AFM) phases, holds significant promise for spintronics applications. This phase transition is thermally influenced and can be controlled by chemical substitution, magnetic fields, lattice strain, and pressure. Measuring the magnetic properties of FeRh, such as magnetoresistance, Hall effect, and Nernst effect, is critical. These time-reversal symmetry-breaking characteristics make FeRh essential for spintronics devices, with the anomalous Hall effect offering potential for field-dependent switching devices.<br/>However, the complexity and precision required for growing FeRh challenge its application at the device level. FeRh is typically grown as a single crystal on MgO substrates, which exhibit minimal lattice strain (c-parameter ~0.5% to 0.62%). While high epitaxial quality is crucial at the experimental stage, it complicates industrial-scale application using methods such as sputtering. Therefore, analyzing the properties of large-area polycrystalline FeRh is essential. Despite its significance, there has been limited analysis of FeRh grown on Si substrates. Observations of polycrystalline FeRh reveal significant magnetic properties. Notably, key indicators of the anomalous Hall effect, such as conductivity and anomalous Hall angle, are robust in both single-crystalline and polycrystalline FeRh on Si substrates.<br/>This study aims to analyze the temperature-dependent magnetic transition and anomalous Hall effect of polycrystalline FeRh grown on Si substrates, providing new insights for developing spintronics devices.