NMR Study of Spin State of Mn²⁺ Impurity in Antiferromagnet CoCl₂·2H₂O

Abstract

The spin state of the isolated Mn²⁺ impurity in the antiferromagnetic phase of CoCl₂·2H₂O is studied by proton NMR. The observed two satellite lines at 1.7 K are revealed to be due to the nearest neighboring protons to Mn²⁺ impurity having the moment of 5 μ_B and 3 μ_B. On the time scale of proton NMR, Mn²⁺ moments are observed to take not the thermal averaged value but each S_z value because of very long relaxation times of Mn²⁺ spin.