Contrasting magnetic ground state in isoelectronic compound Eu ( = Al, Ga)

同じ電子構造を持つEu(=Al, Ga)で実現する対照的な基底状態

金子 耕士   ; 川崎 卓郎   ; 仲村 愛*; 茂吉 武人*; 宗像 孝司*; 中尾 朗子*; 花島 隆泰*; 鬼柳 亮嗣  ; 大原 高志   ; 及川 健一   ; 田村 格良  ; 辺土 正人*; 仲間 隆男*; 大貫 惇睦*

Kaneko, Koji; Kawasaki, Takuro; Nakamura, Ai*; Moyoshi, Taketo*; Munakata, Koji*; Nakao, Akiko*; Hanashima, Takayasu*; Kiyanagi, Ryoji; Ohara, Takashi; Oikawa, Kenichi; Tamura, Itaru; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika*

As a consequence of strong coupling among charge, magnetic and orbital degrees of freedom, a variety of attractive physical properties comes out in Eu compounds. In Eu ( = Al, Ga) with the BaAl-type structure, Eu ions are divalent and, hence, carry magnetism with S = 7/2. These isoelectronic compounds exhibit contrasting magnetic properties. In order to reveal respective ground states from a microscopic point of view, single crystal neutron diffraction experiments were carried out on SENJU at BL18 in MLF. Superlattice peaks were successfully observed in both compounds. The magnetic ground state of EuGa can be described by the commensurate vector. On the other hand, the ground state in EuAl is characterized with the long periodic magnetic structure. This study reveals that, in addition to the transition sequence, the ground state magnetic structures are also different between these compounds.