Hyperfine Fields at ¹⁵³Eu Nuclei in Eu_0.99R_0.01Se (R=Sr and Sm) Studied by NMR

The 153 Eu NMR in Eu 0.99 Sr 0.01 Se and Eu 0.99 Sm 0.01 Se have been observed as a function of temperature in the range between 1.7 and 4.2 K. Each of the resonances in the magnetic phases of the NNS and NSNS types has one or two satellite lines, which are assigned to the nuclei having a Sr or Sm ion on the next nearest neighbor (n.n.n.) sites. The transferred hyperfine field per a n.n.n. Eu 2+ ion is obtained as -(4.1±0.4) kOe from the satellite NMR frequencies. The value agrees with that estimated by using the hyperfine splitting of the Eu 2+ ESR in SrSe, showing that the core polarization fields at the Eu 2+ nuclei in EuSe and SrSe are equal to each other.