Experimental Evidence for Interband Mixing in Rare‐Earth Intermetallic Compounds

Abstract

Abstract Measurements of the Knight shifts and susceptibilities of rare‐earth intermetallic compounds have been extended to YCu, GdCu, TbCu, DyCu, HoCu, and ErCu. The phenomenological exchange constants 𝒥 sf between 4f‐electron spins and conduction‐electron spins are derived to be −0.21 eV. Also the paramagnetic Curie temperatures of the compounds GdCu 1− x Ga x have been measured. The Knight shifts and Curie temperatures are discussed in terms of the Ruderman‐Kittel‐Kasuya‐Yosida theory. For the various series of rare‐earth intermetallic compounds the s‐f exchange integral Γ = 2 J (0) and the Fermi wave vector k F have been determined. Γ is found to be a continuous function of k F , with a sign reversal at k F ≈ 1.4 Å −1 . This observed behavior is consistent with the calculations of Watson, Koide, Peter, and Freeman on the effect of interband mixing on the exchange interactions.