Evidence for Dyakonov-Perel spin relaxation in Gd³⁺ doped YFe₂Zn₂₀

We report on the magnetic, thermodynamic, and electronic properties of the Gd-doped nearly ferromagnetic Fermi liquid (NFFL) system YFe2Zn20 by means of dc magnetic susceptibility, specific heat, and electron spin resonance (ESR) measurements. As Gd is incorporated (Y1-xGdxFe2Zn20; x = 0.005, 0.01, and 0.05), the magnetization measurements present evidence of ferromagnetic correlations with unusual results in temperaturedependent ESR experiments for all samples. Strong evidence of an induced conduction ESR (CESR) is found due to the presence of Gd3+ ions for all of the doped samples. The usual local magnetic moment resonance associated with Gd3+ 4 f localized electrons were only present for x = 0.05, coexisting with the CESR. Although YFe2Zn20 is a NFFL, no CESR was detected for the undoped sample, demonstrating the role of Gd3+ as a CESR activator. These results are discussed in terms of a highly polarized, enhanced Pauli paramagnetism of d-type electrons and a Dyakonov-Perel-like relaxation mechanism involving spin-flip due to magnetic impurities.