NMR Study of an Effective J value in Dilute Ag–Mn Alloys

Abstract

Magnetic susceptibility and NMR measurement on dilute Ag–Mn alloys have been made at temperatures between 1.5 K and 300 K. The manganese concentrations are 25, 42, 81 and 470 ppm. The impurity contribution to the observed line widths is proportional to the impurity concentration and the averaged impurity spin which is determined from the susceptibility data. The effective J value is derived from the proportionality constant as |J|=1.1±0.1 eV. For the derivation of the J value the local field distribution caused by the impurity due to the RKKY interaction and the direct dipolar interaction has been calculated. This magnitude of J is different by a factor of 5.0±0.5 from the value obtained from T_K=40 mK.