[en] An alternative and graphical representation of the magnetic moment and the effective paramagnetic moment for polycrystalline Ce compounds with tetragonal site symmetry is described. The reduced moments can be calculated by means of standard perturbation theory. The calculated values deduced from the ground states of CeCu₂Si₂, CeRu₂Si₂, and CePd₂Si₂ polycrystals are compared with experimental magnetic moments

[en] The effect of a tetragonal crystal field on a J = 5/2 rare earth ion is calculated and is presented in a graphical form giving a complete description of the energy, the individual magnetic moment, and Van Vleck susceptibility of each doublet resulting from the crystal field splitting, as a function of two dimensionless parameters and a scale factor. These magnetic properties, which correspond to terms in H and H² in the development of the energy in presence of a perturbating magnetic field, are given for both the cases, when H is either parallel or orthogonal to the c axis. The results are applied to the compound CeRu₂Si₂. (author)

[en] The effect of a cubic crystal field on rare-earth ions is calculated and presented in a graphical form representing the individual magnetic moment and Van Vleck susceptibility of the lowestlying sub-state, for J = 3.5; 4; 4.5; 6; 7.5; 8. This is a practical guide for analyzing the moderate-field part of the magnetization. The results are given for the three principal directions. In order to analyze susceptibility measurements, the calculated Curie constant (or the Van Vleck susceptibility) of the fundamental multiplet is also represented. (author)

[en] Magnetic measurements are reported for polycrystalline compounds (Tbsub(c)Lasub(1-c))Be₁₃, with 0.02 <= c <= 1, in the temperature range 1.6 to 300 K and for fields up to 70 kOe. The observed ordering temperature Tsub(N) and the downward shift of the inverse susceptibility curve, in the paramagnetic regime (T >= Tsub(N)), scales linearly versus c. The M(H, T) dependences are calculated by diagonalizing the Hamiltonian including crystal field, molecular, and Zeeman terms along the <100>, <110>, and <111> directions. The best fit to the magnetic data is obtained for the crystal field parameters x = -0.8 and W varying linearly from 0.05 K for c = 1 to 0.13 K for c = 0.16. A transition from Van Vleck paramagnetism to an ordered magnetic structure occurs at low temperature, as the terbium concentration exceeds the threshold value for ordering of about c = 0.06. (author)

[en] Searches for radio line emission/absorption from Comet Halley and Comet Giacobini-Zinner were made at the 100-m Effelsberg Telescope in late 1985/early 1986. No detections were made for the K-band lines of water and ammonia, the ground state rotational transition of formaldehyde, or the excited lambda-doublet transitions of OH. Strong emission lines of the ground state OH molecule were observed in late January 1986. 15 references

[en] The magnetic properties of the Laves phase series Gd(Fesub(1-x)Alsub(x))₂ have been studied by means of magnetisation measurements in fields up to 160 kOe for 0 =< x =< 1.0. The Curie temperatures show a rapid decrease with increasing x values, followed by a slight increase for x => 0.8. The mean magnetic moment increases almost linearly from GdFe₂ to GdAl₂. This implies a constant iron moment for all iron atoms throughout the whole concentration range. The Gd atoms appear to be the magnetising element of the diluted Al-Fe matrix. (author)

[en] The magnetic behavior of Y(Fesub(1-c)Alsub(c))₂ alloys (T=4 K, 0<=c<1) is described in a local model. This model accounts for the variation with c of the spontaneous magnetization related to magnetic Fe atoms (with at least 15 Fe neighbours) and the high-field susceptibility which arises from the non-magnetic Fe atoms. (Auth.)

No abstract available

[en] Magnetic and neutron diffraction measurements are reported. These compounds which order magnetically for 0 < approx. c <= 1, are helimagnetic at least for c > approx. 0.40. Cubic symmetry crystal field effects on Tb³⁺ yield to a 10 K overall splitting a GAMMA₃ non magnetic doublet being the ground state at 0.7 K below a GAMMA₅¹ triplet. (orig./SMV)

[en] The fcc-Ce₃In compound is presented as the best available approximation to reproduce the main magnetic properties of γ-Ce at low temperatures, where such pure phase does not exist. The electronic specific heat shows a maximum at 18K and an anomaly at 2.2K, with an entropy of 0.8Rln at 32K. The susceptibility shows a broad maximum at 1.8K, while in the magnetization there are no trace of ordering up to 18 Tesla at 1.5 and 4.2K. The experimental results are interpreted as governed by a quadruplet crystal field ground state, which undergoes a quadrupolar transition at 18K. At lower temperatures a heavy fermion ground state developes with C_el/T = 500 mJ/Ceat.K² for T → 0 and χT/C_el = 0.ll emu K/J for T < 5K. (Author)