Exploration for multipole order in 5-electron systems; X-ray magnetic circular dichroism study of BaCaOsO

5電子系における多極子秩序の探索; BaCaOsOのX線磁気円二色性

芝田 悟朗 ; 林 浩章*; 河村 直己*; 岡本 淳*; Huang, D. J.*; 田中 新*; Streltsov, S.*; 山浦 一成*; 藤森 淳*

Shibata, Goro; Hayashi, Hiroaki*; Kawamura, Naomi*; Okamoto, Jun*; Huang, D. J.*; Tanaka, Arata*; Streltsov, S.*; Yamaura, Kazunari*; Fujimori, Atsushi*

The double perovskite-type (DP) oxide BaCaOsO with electron configuration is one of the candidates for magnetic octupole order. In the present study, we investigated the Os 5 electronic structure of BaCaOsO polycrystals under magnetic fields via Os -edge hard X-ray magnetic circular dichroism (XMCD). In contrast to conventional XMCD spectra of 3 and 4 electron systems, relatively large (%) XMCD signal was observed at the -edge, whereas it is weak (%) at the edge, suggesting a large orbital magnetic moment due to the strong SOI of Os 5 electrons. The overall line shapes of the XAS and XMCD spectra can be simulated by atomic multiplet calculations with cubic symmetry. The calculations show that Coulomb interaction is weak compared to Os 5 SOI, suggesting that SOI plays an importance role in the electronic structure of BaCaOsO.