Microscopic Origin of the Metamagnetic Transition in Co(S_<i>x</i>Se_1-<i>x</i>)₂–⁵⁹Co NMR

Abstract

From 59 Co NMR experiments in metallic compounds Co(S x Se 1- x ) 2 with pyrite structure, it is shown that the concentration and external field dependences of the magnetism are manifested by inhomogeneous distribution of ferromagnetic Co atoms with 0.85 µ B and nonmagnetic Co atoms. Particularly, the field induced metamagnetic transition found in x =0.88 and 0.86 is concluded to be due to the progressive-discontinuous transitions from the nonmagnetic to the ferromagnetic states with increasing external field. The field dependence of the NMR intensity associated with the nonmagnetic Co atoms accounts entirely for the magnetization vs field curves.