Hyperfine Interactions in the Ground State and 21.7-keV State ofEu151in Europium Iron Garnet

Abstract

The hyperfine interaction of the ground state and 21.7-keV state of ${\mathrm{Eu}}^{151}$ in europium iron garnet have been measured at 300, 81, and 20°K using the technique of Mössbauer absorption. Values of (335±50), (570±35), and (670±100) kOe were found for effective magnetic fields acting on the Eu nuclei in europium iron garnet at the temperatures of 300, 81, and 20°K, respectively. These values are in agreement with theoretical calculations of the nondiagonal matrix elements associated with the admixture of states produced by the exchange interaction. The value of the quadrupole interaction $e{Q}_0{q}_{\mathrm{eff}}$ of the ground state of ${\mathrm{Eu}}^{151}$ in europium iron garnet was found to be (-240±100) Mc/sec at 81°K. The results yield an assignment of a spin of $\frac{7}{2}$ for the 21.7-keV level and a value of $\mu =(2.54\mathrm{}\pm 0.15)$ nm for the magnetic moment of this level.