Temperature dependence of the effective Gilbert damping constant of FeRh thin films

Antiferromagnetic (AFM) materials have attracted attention for device applications due to the absence of the stray field and high-frequency response. To integrate AFM materials into magnetic devices, the understanding of the interfacial effect between AFM and ferromagnetic (FM) materials is required. In particular, magnetization dynamics and magnetic damping are critical phenomena to be elucidated since they govern magnetization switching, spin-wave propagation, etc. Although a conventional method for studying the interfacial effects is stacking materials, the approach may cause unfavorable factors. To get insight into the dynamic properties at the AFM and FM interfaces, we have focused on B2-ordered FeRh, showing the first-order phase transition from the AFM to FM states, since the coexistence of AFM and FM domains occurs during transitions, which is an ideal platform for studying interfacial effects. For this study, we have studied ferromagnetic resonance (FMR) of FeRh thin films during the AFM-FM phase transition as a function of temperature. From the FMR measurements, we characterize the temperature dependence of the effective Gilbert damping constant alpha (eff). We find that alpha (eff) decreases with increasing temperature, indicating that the temperature variation of the effective Gilbert damping constant originates from the exchange interaction between the AFM and FM domains in the film and/or AFM domains as a spin sink.

Automated summary

Antiferromagnetic materials are of interest for device applications due to their lack of stray field and high-frequency response. Understanding the interfacial effects between antiferromagnetic and ferromagnetic materials, particularly magnetization dynamics and magnetic damping, is crucial for integrating them into magnetic devices. By studying the B2-ordered FeRh with a first-order phase transition from antiferromagnetic to ferromagnetic states, researchers can gain insight into the dynamic properties at the interface, such as the temperature dependence of the effective Gilbert damping constant.