Local magnetic behavior OF ~(54)Fe in EuFe_2As _2 and Eu_(0.5)K_(0.5)Fe_2As_2: Microscopic study using time differential perturbed angular distribution (TDPAD) spectroscopy

摘要

In this paper, we report the time differential perturbed angular distribution measurements of ~(54)Fe on a polycrystalline EuFe _2As_2 and Eu_(0.5)K_(0.5)Fe _2As_2. The hyperfine field and nuclear spin-relaxation rate are strongly temperature dependent in the paramagnetic state suggesting strong spin fluctuation in the parent compound. The local susceptibility show Curie-Weiss-like temperature dependence and Korringa-like relaxation in the tetragonal phase indicating the presence of local moment. In the orthorhombic phase, the hyperfine field behavior suggesting quasi two-dimensional magnetic ordering. The experimental results are in a good agreement with first-principle calculations based on density functional theory.