Antiferromagnetic order of the Co high-spin state with a large orbital angular momentum in LaCaCoO
層状ペロブスカイト型コバルト酸化物LaCaCoO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 LaCaCoO 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 1.10.1 and 1.00.1, 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.