A¹⁵¹Eu Mossbauer study of the magnetic hyperfine interactions in the metallic compound Eu₂Co₁₂P₇containing trivalent europium

Abstract

Magnetic susceptibility measurements of Eu2Co12P7 show a ferromagnetic phase transition at the Curie temperature of TC=151+or-0.5 K, which is attributed to the magnetic order of the cobalt sublattice. 151Eu Mossbauer spectra reveal an unusual magnetic hyperfine structure splitting of the Van Vleck ion Eu3+. The temperature dependence of the magnetic flux density at the 151Eu nuclei was determined and compared with theoretical values. The exchange field acting on the europium ions may be assumed to follow the Brillouin function, where the best agreement is achieved for J=1. An exchange constant of mu BBexch(0)/k=7.5+or-0.1 K was deduced from the saturation value of the magnetic flux density Bsat=19.0+or-0.1 T. The possible contributions of Fermi contact terms of the magnetic flux density are discussed.