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Mössbauer Study of Ni 0.995 57 Fe 0.005 S 2 –Magnetic Structure of NiS 2 –

1975; Physical Society of Japan; Volume: 39; Issue: 1 Linguagem: Inglês

10.1143/jpsj.39.63

1347-4073

Yoshikazu Nishihara, Shinji Ogawa, Shinya Waki,

Iron-based superconductors research

Mössbauer experiment has been performed of 57 Fe doped in antiferromagnetic NiS 2 . The supertransferred hyperfine field of 19 kOe has been observed at 4.2 K. From the analysis of the supertransferred hyperfine field, it is concluded that NiS 2 has a non-collinear spin structure. The Ni spins with ordering of the first kind for fcc lattice make a constant angle θ with the principal axis of the electric field gradient at the Ni sites. The angle θ is (12±4)° above 30 K and (21±6)° below 30 K. The component of Ni spin with the first kind ordering varies smoothly through 30 K. No anomaly has been observed in the isomer shift and the quadrupole splitting at 30 K and at Néel temperature of 54 K. The quadrupole splitting is -(0.27±0.01) mm/sec at 295 K. An effect of u parameter of crystal lattice can explain the negative sign and the weak temperature dependence of the quadrupole splitting of 57 Fe in NiS 2 .