Electron spin resonance ofGdxLa1−xPd3intermetallic compounds

Abstract

Electron spin resonance of Gd in ${\mathrm{Gd}}_{x}{\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Pd}}_{3}$ intermetallic compounds annealed at 740 and 840\ifmmode^\circ\else\textdegree\fi{}C exhibit a dependence of linewidths and $g$ shifts on the annealing temperature. The linewidths and $g$ shifts were measured as functions of temperature and concentration of Gd. Samples with high Gd concentration (1 at.% or more) were found to have bottleneck effects. All samples annealed at 740\ifmmode^\circ\else\textdegree\fi{}C were found to exhibit Korringa-like thermal broadening between 20 and 40\ifmmode^\circ\else\textdegree\fi{}K and those annealed at 840\ifmmode^\circ\else\textdegree\fi{}C were found to be Korringa-like between 6 and 35\ifmmode^\circ\else\textdegree\fi{}K. Below 20\ifmmode^\circ\else\textdegree\fi{}K, samples annealed at 740\ifmmode^\circ\else\textdegree\fi{}C were found to exhibit ordering effects whereas samples annealed at 840\ifmmode^\circ\else\textdegree\fi{}C did not show such effects even at 6\ifmmode^\circ\else\textdegree\fi{}K. These differences are indicative of the difference in the structural composition of the lattice due to annealing. We have deduced the average values for the exchange integral $J$ to be 0.16 \ifmmode\pm\else\textpm\fi{} 0.03 eV and 0.15 \ifmmode\pm\else\textpm\fi{} 0.03 eV for the samples annealed at 740 and 840\ifmmode^\circ\else\textdegree\fi{}C, respectively. We have obtained also the magnitudes of two contributions to the conduction-electron relaxation rates to the lattice (i) due to undisturbed host lattice and (ii) by spin-flip scattering due to Gd.