Polarized Neutron Experiments on REBa 2 Cu 3 O 7—δ with Polarization and Time of Flight Energy Analysis

Experimental data on HoBa 2 Cu 3 O 7—δ (with δ = 0 and 1), obtained with a diffuse neutron scattering instrument and employing full polarization analysis, are used to evaluate the magnetic scattering cross sections. The validity of the evaluation is confirmed by a comparison with calculations based on published crystal field parameters for this compound. Similar experiments on Tm‐ and Yb‐substituted materials and the corresponding evaluations show, that both ions are in a 3 + state (Tm 3+ , Yb 3+ ) at low temperature, whereas a change of valence occurs somewhere below 300 K.