Lanthanide magnetic effects

The other lanthanides ions do not obey this simple relationship. The 4/electrons are well shielded from the entemal field by the overlying 5s and 5p electrons. Thus, the magnetic effect of the motion of the electron in its orbital is not quenched out. Thus, the magnetic moment must be calculated taking into account both the magnetic moment from the unpaired electron spins and that from the orbital motion. In lanthanides the spin contribution S and orbital contribution L couple together to give a new quantum number J. 

In this review, we have attempted to survey what has been learned so far about lanthanide magnetism from both elastic and inelastic neutron scattering experiments. In a field as vast as this, there have inevitably had to be several omissions. Thus, we have had to omit discussions of critical scattering from lanthanide systems, of the very interesting studies of cooperative Jahn-Teller effects in some rare earth compounds, of measurements of the phonon spectra of these systems, and of a large number of neutron diffraction studies of many rare earth compounds other than those described in section 3.5. 

Third, and finally, it has been established that the lanthanide magnetism is in general remarkably robust, and in particular is insensitive to the interfaces, even in crystals only a few atomic layers thick. A reservation of critical importance in this regard is the central role of the state of strain in the description of the magnetic behavior. Specifically it has been established for Dy that epitaxial strains 2% are sufficient to double the Curie temperature or completely suppress the ferromagnetic phase. The twin assets of robustness and strain sensitivity make these materials at one time both ideal systems with which to explore epitaxial effects, and attractive models with which new states of magnetic order may be designed and synthesized. 

If the point symmetry group of the lanthanide ion does not possess an inversion, the magnetization linear in an external electric field may be observed, and the dielectric susceptibility of the sample may be also radically affected by an external or internal magnetic field. Electric field effects on the EPR spectra of the lanthanide ions in insulators are well known (see, for example, Sakharov 1979, 1980), and here we shall consider only the alteration of the dielectric properties of the crystal due to the ordering in the lanthanide subsystem. Dielectric measurements are often used to plot the phase boundaries of the lanthanide magnets in the magnetic field. The eneigy of the lanthanide ion in the quasistatic electric field is presented in eq. (9). The effective even dipole moment of the ion can be written as follows... 

Many dHvA measurements were performed in Ce compounds. The 4f-localized compounds such as CeGa2 and CeRu2Ge2, which do not show the many-body Kondo effect, are similar to the corresponding La compounds in topology of the Fermi surface. The detected cyclotron mass is not large, comparable to those of the other lanthanide magnetic compounds. 

From the latter equation the calculated boiling point of Cm is 3110°C. The derived heat of fusion, entropy of fusion, and average second-law entropy are 13.85 kJ mol , 9.16 JK mol , and 106.7 3.0 J K mol , respectively. Low-temperature condensed-phase thermodynamic parameters await the availability of long-lived isotopes. For excellent discussions of thermodynamic, electronic, and magnetic effects in curium and other actinide and lanthanide metals, the reader is referred to recent articles by Ward and Hill [34]. 

Figure 1.2 Energetic structure of a Kramers lanthanide ion in a ligand field evidencing the effect of progressively weaker perturbation. The magnetic field effect is estimated assuming a 1T field.

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