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Magnetic Properties of Cobalt and Nickel Dichalcogenide Compounds with Pyrite Structure

1969; Physical Society of Japan; Volume: 26; Issue: 3 Linguagem: Inglês

10.1143/jpsj.26.631

1347-4073

Kengo Adachi, Kiyoo Satō, Motohiko Takeda,

Heusler alloys: electronic and magnetic properties

The magnetic properties of dichalcogenide compounds, CoS 2 , CoSe 2 , NiS 2 , NiSe 2 and the system Co(S x Se 1- x ) 2 , were studied by means of magnetic measurement, neutron diffraction and NMR. The exchange interaction J s w of the ferromagnetic CoS 2 ( T c =124°K, θ p =220°K, p eff =1.76µ B , n =0.84µ B and H i =52 kOe) was estimated to be 24 cm -1 per Copair from the analysis of spin wave theory. While, CoSe 2 ( T N =90°K, θ p =-160°K and p eff =1.72µ B ) showed an antiferromagnetic spin ordering with MnSe 2 type. NiS 2 (θ p =-740°K and p eff =2.48µ B ) had no magnetic ordering even at 4.2°K. NiSe 2 exhibited weak constant paramagnetism with metallic conductivity. In Co(S x Se 1- x ) 2 , (0≤ x ≤1), the magnetic properties and the magnetic phase diagram were determined, and this system showed to have “low spin state” with 1µ B per Co. Some discussions were given from the theoretical stand points.