X-ray magnetic circular dichroism of a valence fluctuating state in Eu at high magnetic fields
高磁場下でのEuの価数揺動状態のX線円二色性
松田 康弘*; Ouyang, Z. W.*; 野尻 浩之*; 稲見 俊哉; 大和田 謙二; 鈴木 基寛*; 河村 直己*; 光田 暁弘*; 和田 裕文*
Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Inami, Toshiya; Owada, Kenji; Suzuki, Motohiro*; Kawamura, Naomi*; Mitsuda, Akihiro*; Wada, Hirofumi*
価数揺動を示す二つの物質(EuNi
(Si
Ge
)
とEuNi
P
)についてEuのL吸収端でX線磁気円二色性(XMCD)を40Tの高磁場まで測定した。磁気的な2価のEuからの主要なXMCDに加え、非磁性の3価のEuからの明瞭なXMCDが観測された。この結果はどちらの価数の5d電子は磁気的に偏極していることを示している。また、それぞれの価数での5d電子の偏極度の比は物質依存であることも示された。XMCDの起源に対する可能な説明と偏極度の比の物質依存性についての説明を伝導電子とf電子の混成の点から議論する。
X-ray magnetic circular dichroism (XMCD) at the Eu L edge in two compounds exhibiting valence fluctuation, namely EuNi
(Si
Ge
)
and EuNi
P
, 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.