ESR Study of Hyperfine Coupling Constants of Eu²⁺ in Alkaline Earth Chalcogenides –Transferred Hyperfine Field in Eu-Chalcogenides

Abstract

The hyperfine (hf) fields at isolated Eu 2+ ions in alkaline earth chalcogenides are measured by ESR method to make a separation between the core polarization and transferred contributions to the hf field at the Eu nucleus in Eu-chalcogenides. The Eu hf fields, which are assumed to be equal to the core polarization fields in Eu-chalcogenides, are (-)299, (-)300, (-)292 and (-)283 kOe in SrO, SrS, SrSe and SrTe, respectively. Using NMR data, the transferred hf fields at Eu nuclei are estimated as -8, -32, -38 and -30 kOe in the ferromagnetic states of EuO, EuS, EuSe and EuTe, respectively. The variation of the transferred hf field from EuO to EuTe is correlated to the exchange mechanism involving 5d and 6s electron states.