We succeeded in growing high-quality single crystals of pyrite-type cubic compounds CoSe2 and CoS2 using a transport agent of CoBr2 and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization, and the de Haas-van Alphen (dHvA) effect. We confirmed that CoSe2 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/(K2•mol). On the other hand, CoS2 is a ferromagnet with a Curie temperature T C = 122 K and an ordered moment μs = 0.93 μB/Co. The γ value of 21 mJ/(K2•mol) in CoS2 is slightly larger than that of CoSe2. A large ordered moment, together with a large γ value, is a characteristic feature in CoS2 because CoS2 is a half-metallic spin state in the ferromagnetic state. Correspondingly, we detected a main dHvA branch with a large cyclotron effective mass of 13m 0 in the dHvA experiments. The detected dHvA branches in CoS2 and CoSe2 are discussed on the basis of the results of energy band calculations, revealing a broken four-fold-symmetry in the angular dependence of the dHvA frequency.
|Journal||Journal of Physics: Conference Series|
|Publication status||Published - 2017 Apr 6|
|Event||18th International Conference on Strongly Correlated Electron Systems, SCES 2016 - Hangzhou, China|
Duration: 2016 May 9 → 2016 May 13