Crystalline electrical field effects on powdered RE Cu4Al8 (RE = Tb, Dy, Ho and Er) intermetallic compounds

Abstract

In this work, structural and magnetic properties RE Cu4Al8 (RE = Tb, Dy, Ho and Er) family of compounds are reported. Measurements of X-ray diffraction, tem- perature (T) and magnetic eld (H) dependencies of magnetization are presented for each compound. The analysis of X-ray diffraction patterns shows a small variation in a (8.705824?8.734991 Å) and c (5.123802?5.135258 Å) lattice parameters as a function of the rare earth. The T-dependent magnetic susceptibility reveals the Curie-Weiss-like behavior at high-T evolving to antiferromagnetic transitions at low-T (6 < TN < 28 K) for all studied materials. Measurements of magnetization as a function of magnetic eld show eld-induced transitions for RE = Dy, Ho and Er, which present larger magnetic moments, though no magnetic saturation is attained (4.4 < Mmax < 7.3 μB) for none of the studied compounds. This fact is an indicative of strong crystalline electrical eld (CEF) effects. We have conducted a detailed analysis, based on a mean- eld spin model, in order to determine the CEF parameters from the macroscopic data of the studied powdered samples. Finally, to show the reliability of our calculations, the obtained CEF energy levels and wave functions are compared with previous CEF studies in single crystalline samples of ErCu4Al8, including results obtained from inelastic neutron scattering data.