Conduction electron density of states and proton spin-lattice relaxation in the dihydrides of scandium, yttrium, lanthanum and lutetium

Abstract

We report determinations of the proton Korringa product T 1 e T in the dihydride phases of scandium, yttrium, lanthanum and lutetium based on samples prepared from the highest purity metals available in the Ames Laboratory and in addition in some cases utilizing the technique of partial deuteration to suppress further the paramagnetic impurity contribution to the spin-lattice relaxation rate. We conclude that the quantity (T 1e T) − 1 2 , which is essentially proportional to the electronic density of states N ( E F ), has the value 0.055 ± 0.002 s − 1 2 K − 1 2 at the dihydride composition in all systems. The dependence of ( T 1e T) − 1 2 on hydrogen concentration within the dihydride phase appears to be weak; however, in LaH x ( T 1 e T ) − 1 2 decreases substantially for x ⪢ 2 indicating a decrease in N ( E f ) in this hydrogen concentration range. The implications of these results for relative s and d band contributions and hyperfine fields are discussed in the light of recent low temperature heat capacity measurements.