著者

Teruya Atsushi Suzuki Fuminori Aoki Dai Honda Fuminori Nakamura Ai Nakashima Miho Amako Yasushi Harima Hisatomo Hedo Masato Nakama Takao Onuki Yoshichika

出版者

The Physical Society of Japan

雑誌

Journal of the Physical Society of Japan (ISSN:00319015)

巻号頁・発行日

vol.85, no.6, pp.64716-1-10, 2016-06-01

被引用文献数

11

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We succeeded in growing high-quality single crystals of the pyrite-type cubic compounds CoSe₂and CoS₂using the transport agent CoBr₂and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization, and de Haas–van Alphen (dHvA) effect. We confirmed that CoSe₂is an exchange-enhanced paramagnet revealing a broad maximum at around 50 K in the temperature dependence of the magnetic susceptibility. The electronic specific heat coefficient is moderately large, γ = 18 mJ/(K²·mol). On the other hand, CoS₂is a ferromagnet with a Curie temperature <italic>T</italic>_C= 122 K and an ordered moment μ_s= 0.93 μ_B/Co. The γ of 21 mJ/(K²·mol) of CoS₂is slightly larger than that of CoSe₂. A large ordered moment, together with a large γ, is characteristic of CoS₂because CoS₂is a half-metallic spin state in the ferromagnetic state. Correspondingly, we detected a main dHvA branch with a large cyclotron effective mass of 13<italic>m</italic>₀in the dHvA experiments. The detected dHvA branches in CoS₂and CoSe₂are discussed on the basis of the results of energy band calculations, revealing a broken fourfold symmetry in the angular dependence of the dHvA frequency.