- 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
We succeeded in growing high-quality single crystals of the pyrite-type cubic compounds CoSe<sub>2</sub>and CoS<sub>2</sub>using the transport agent CoBr<sub>2</sub>and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization, and de Haas–van Alphen (dHvA) effect. We confirmed that CoSe<sub>2</sub>is 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/(K<sup>2</sup>·mol). On the other hand, CoS<sub>2</sub>is a ferromagnet with a Curie temperature <italic>T</italic><sub>C</sub>= 122 K and an ordered moment μ<sub>s</sub>= 0.93 μ<sub>B</sub>/Co. The γ of 21 mJ/(K<sup>2</sup>·mol) of CoS<sub>2</sub>is slightly larger than that of CoSe<sub>2</sub>. A large ordered moment, together with a large γ, is characteristic of CoS<sub>2</sub>because CoS<sub>2</sub>is 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><sub>0</sub>in the dHvA experiments. The detected dHvA branches in CoS<sub>2</sub>and CoSe<sub>2</sub>are discussed on the basis of the results of energy band calculations, revealing a broken fourfold symmetry in the angular dependence of the dHvA frequency.