X-ray magnetic circular dichroism of a valence fluctuating state in Eu at high magnetic fields

Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Inami, Toshiya; Owada, Kenji; Suzuki, Motohiro*; Kawamura, Naomi*; Mitsuda, Akihiro*; Wada, Hirofumi*

X-ray magnetic circular dichroism (XMCD) at the Eu L edge in two compounds exhibiting valence fluctuation, namely EuNi(SiGe) and EuNiP, has been investigated at high magnetic fields of up to 40T. A distinct XMCD peak corresponding to the trivalent state (Eu), whose ground state is nonmagnetic (J = 0), was observed in addition to the main XMCD peak corresponding to the magnetic (J = 7/2) divalent state (Eu). This result indicates that the 5 electrons belonging to both valence states are magnetically polarized. It was also found that the ratio (3+)/(2+) between the polarization of 5 electrons() in the Eu state and that of Eu depends on the material. The possible origin of the XMCD and an explanation of the material dependence of (3+)/(2+) are discussed in terms of hybridization between the conduction electrons and the f electrons.