J.N. Daou

Electrical resistivity of the α-phase lutetium-hydrogen at low temperature

Abstract The resistivity of the solid solutions LuH x for 0 ⩽ x ⩽ 0.235 is measured between 4.2 and 300 K. The maximum α-phase solubility is found for x = 0.2 in the whole temperature range investigated. A resistivity anomaly is observed in hydrogen containing specimens and its possible origin of anomalous behavior is discussed.

Kondo Lattice and Magnetic Behaviour in the CeH2+x System (0 ≤ x ≤ 0.1)

Electrical resistivity measurements on CeH2+x specimens show and incoherent and a coherent Kondo lattice behaviour above and below T ≈ 20 K, respectively. The incoherent term has a log T variation showing the influence of the crystal-field degeneracies. We observe also low-temperature anomalies related to magnetic transitions which tend to disappear when atomic disorder is introduced by quench into the sublattice of the supplementary (x) H-atoms. The coefficient of the low-temperature (T 2 K) T2-law of ρ(T) is in good agreement with the heavy-fermion model.

Electrical resistivity of rare earth dihydrides and dideuterides

Abstract The electrical resistivities of thulium, erbium, dysprosium, gadolinium and their dihydrides and dideuterides were measured below room temperature. Special attention was given to the coupling of the electrons with optical hydrogen (deuterium) vibrations. We found it to be about three times smaller than the corresponding coupling to the acoustic or host atom vibrations. The latter is also smaller in the dihydrides than in the pure metals. These data are discussed on the basis of recent theoretical models dealing with the electronic structure of the dihydrides; the implications relative to the occurrence of superconductivity and magnetism are also briefly discussed.

α-HoH(D)x: a new hydrogen-rare earth solid-solution system at low temperatures

Abstract The terminal low-temperature solubility of hydrogen in holmium has been determined resistometrically as x max = 0.03 ± 0.005 at.H(D)/at.Ho, leading to a residual-resistivity increase of Δϱ/Δx = 2.5 ± 0.5 μΩ cm/at.% H(D) and to decrease of the Neel temperature by about 2 K/at.% H(D). A quench-sensitive resistivity anomaly at 174 and at 179 K for respectively α-HoH x and α-HoD x is observed and attributed to short-range ordering of H-atoms, in analogy to other rare earth-hydrogen systems.

Recovery of low-temperature electron-irradiated lutetium

Abstract The annealing spectrum of electron-irradiated Lu has been studied between 14 and 135 K and a tentative interpretation of the observed structure given. A comparison with other irradiated h.c.p. metals indicates that the c/a -ratio might be an important parameter for the determination of the interstitial-atom mobility.

A neutron-diffraction study of the magnetism in α-ErDx solid solutions

Abstract The influence of deuterium upon the magnetic transitions in Er has been studied by neutron diffraction on α-ErDx powder specimens, with 0 ⪕ x ⪕ 0.03. We have observed a decrease of TN and of TH upon the addition of D, in agreement with other techniques and with a model implying a decrease of thedensity of states at the Fermi surface. An increase of the transition width at TH could be related to a stabilisation of the basal plane component of the moment by D. The simultaneous increase of TC, however, could not be attributed to an opening up of the vertex angle of the ferromagnetic cone, as the latter appears to be independent of the D-contents in the sample.