Local moment hyperfine studies of the Kondo system PdHxFe0.003

Abstract

The effect of hydrogen on the Fe giant moment in dilute PdFe and the resulting single moment Kondo and RKKY interactions in PdHxFe is investigated by Mössbauer hyperfine techniques in an external magnetic field. The results show that within a large range of composition within the α′ phase (hydrogen lattice liquid), μ(Fe) remains constant at about 3.9μB, smaller than the 12.6μB in dilute PdFe. The Kondo temperature TK is found to increase with hydrogen, as determined from the usual X=μH/k(T+ϑ) modification to the Brillouin function B1(X) where ϑ=4.5 TK. The dynamic part of the impurity interactions leads to a spin-glass–type spin-spin relaxation, which produces a line broadening in a magnetic field much larger for the outer Mössbauer lines and with a maximum in field at about X=1. At higher concentrations (x=0.76), the saturation HF field decreases, indicating a possible orbital component on μ(Fe); this conforms with certain recent calculations. Above x=0.8, new Mössbauer lines are found, indicating the phase transitions and two-phase regions α′ → β and β → α″ with increasing hydrogen content.