Study on irradiation-induced magnetic transition in FeRh alloys by means of Fe K-edge XMCD spectroscopy

We have studied the effects of swift heavy ion irradiation on the magnetic properties of Fe–50at.%Rh intermetallic compound by using Fe K-edge X-ray magnetic circular dichroism (XMCD) at 20 K. For an unirradiated specimen, no signal of XMCD spectrum has been observed because Fe–50at.%Rh intermetallic compound is intrinsically anti-ferromagnetic below room temperature. For the specimens irradiated with 120–200 MeV Ni, Kr, Xe or Au ions, we have found XMCD spectra which are characterized by a dispersion-type profile with a positive peak and a negative peak near Fe K-edge. The intensity of XMCD spectra remarkably depends on ion-fluence and ion-mass. The experimental result implies that the ferromagnetic state is induced by the swift heavy ion irradiation. The change in magnetic state of Fe element is discussed in terms of energy deposition through the elastic and electronic processes.