Electron spin resonance of Gd3+ in the intermetallic Gd1–xYxNi3Ga9 (0 ≤ x ≤ 0.90) compounds

Abstract

In this work, experiments of X-ray diffraction, magnetic susceptibility, heat capacitance, and Electron Spin Resonance (ESR) carried out in the Gd1–xYxNi3Ga9 (0 ≤ x ≤ 0.90) compounds grown through a Ga self flux method are reported. The X-ray diffraction data indicate that these compounds crystallize in a trigonal crystal structure with a space group R32. This crystal structure is unaffected by Y-substitution, which produces a monotonic decrease of the lattice parameters. For the x = 0 compound, an antiferromagnetic phase transition is observed at TN = 19.2 K, which is continuously suppressed as a function of the Y-doping and extrapolates to zero at x ≈ 0.85. The ESR data, taken in the temperature range 15 ≤ T ≤ 300 K, show a single Dysonian Gd3+ line with nearly temperature independent g-values. The linewidth follows a Korringa-like behavior as a function of temperature for all samples. The Korringa rates (b = ΔH/ΔT) are Y-concentration-dependent indicating a “bottleneck” regime. For the most diluted sample (x = 0.90), when it is believed that the “bottleneck” effect is minimized, we have calculated the q-dependent effective exchange interactions between Gd3+ local moments and the c-e of 〈Jf−ce2(q)〉1/2 = 18(2) meV and Jf−ce(q=0) = 90(10) meV.