Antiferromagnetic order of the Co
high-spin state with a large orbital angular momentum in La
Ca
CoO
層状ペロブスカイト型コバルト酸化物La
Ca
CoO
の大きい軌道磁気モーメントを持つ高スピン状態における反強磁性
岡本 淳*; 中尾 裕則*; 山崎 裕一*; 和達 大樹*; 田中 新*; 久保田 正人
; 堀金 和正*; 村上 洋一*; 山田 和芳*
Okamoto, Jun*; Nakao, Hironori*; Yamasaki, Yuichi*; Wadachi, Hiroki*; Tanaka, Arata*; Kubota, Masato; Horigane, Kazumasa*; Murakami, Yoichi*; Yamada, Kazuyoshi*
The antiferromagnetic insulator La
Ca
CoO
has been investigated by Co L
-edge and O K-edge X-ray absorption spectroscopy (XAS) measurements and Co L
-edge resonant soft X-ray magnetic scattering (RXMS)measurement to determine the Co electronic structures associated with magnetic ordering. Co L
-edge linear-dichroic XAS shows that Co
takes a high-spin (HS) state and Co
takes a low-spin (LS) state. Using Co L
-edge RXMS, we directly determined that an antiferromagnetic order is formed with a HS state of Co
ions. Moreover, the spin and orbital angular momenta of the Co
HS state are quantitatively estimated to be 1.1
0.1 and 1.0
0.1, respectively, and to align parallel in the ab plane by utilizing the cluster model calculation. The large orbital angular momentum of the Co
HS state originates from the small
-symmetry crystal field splitting of
levels, which is comparable with the spin-orbit coupling constant of the Co 3
orbital.