Many macroscopic, magnetic properties of compounds are determined by single-ionic properties of magnetic ions, which are part of the stoichiometric composition. It is well known that the biggest influence on the magnetic ions has their surrounding in the structure of the crystal. The capability of precise influence of ligands gives the chance of stating the magnetic properties on the basis of the fine electronic structure. Taking into consideration, that the individual population of the energy levels of this structure in different temperatures enable to define the temperature dependencies of such thermally dependent properties as: free energy, magnetic entropy, magnetic susceptibility (calculated for various directions of crystals), f -electronic contribution to specific heat, structure of discreet electron levels and the probability of the INS (Inelastic Neutron Scattering) transitions, magnetic anisotropy, spin and orbital contribution to angular momentum of 4 f - shell and many more.
All the above properties properties can be used to check the reliability of the CEF parameters derived from different experiments (ESR, Mössbauer spectroscopy, Raman scattering). However, the most powerful tool to study the CEF effects is given by the inelastic neutron scattering (INS) technique, especially in optically opaque metallic systems.
Useful relationships between units:
[1 K = 0.0862 meV = 1.38·10 -23 J, ( K - Kelvin)]
[ μ B -Bohr magnetron]
[ μ B /T× ion - Bohr magneton/Tesla×ion ] ( μ B/T × ion = 0.5586 emu/mol)
M[μ B/ f.u.] ( 1μ B = 9.27 ·10-24 J/T, J/T = A × m2 ) [μ B× T/kB = 0.67171 K]
Details of Theory
- Entropy S(T)
- Specific heat Cmol(T)
- Magnetic moment and influence of the external magnetic field for it m(B,T)
- Magnetic susceptibility along different crystal directions χi(T)
- Visibility of the energy levels in spectroscopy <Γi|J_|Γj>, <Γi|J+|Γj> , <Γi|JZ|Γj>
- Spin and orbital momenta of the magnetic ion in solid <Γi|L|Γi>, <Γi|S|Γi>