Study on ferromagnetic ordering of FeRh thin films induced by energetic heavy ion irradiation by means of X-ray Magnetic Circular Dichroism

We investigated the ion irradiation induced ferromagnetic state of FeRh thin films with 10 MeV I ion beam by the measurements of a superconducting quantum interference device (SQUID) magnetometer as well as of soft X-ray Magnetic Circular Dichroism (XMCD). It was clearly shown in the magnetization loops by SQUID measurements that the ion irradiation induced the ferromagnetic state in the FeRh thin films even below room temperature. This was also confirmed by the Fe L2,3-edge XMCD measurements for the irradiated FeRh film samples. However, we found that the irradiation ion fluence dependence on the magnetization was totally different between two measurement techniques. We also revealed by XMCD sum rule analysis that the ferromagnetism in the ion irradiated FeRh thin films was mainly dominated by the spin moment.