Magnetic properties Pauli

Nonrelativistic quantum mechanics, extended by the theory of electron spin and by the Pauli exclusion principle, provides a reliable theory for the computation of atomic spectral frequencies and intensities, of cross sections for scattering or capture of electrons by atomic systems, of chemical bonds and many properties of solids, including magnetic properties, although with much more complicated systems it has not always proved possible to develop with adequate accuracy the consequences of the theory. Quantum mechanics has also had a limited success in nuclear theory although m this field it is possible that a more fundamental system of mechanics is required. 

Magnetic Susceptibility of TiNi has been previously observed [39] to be temperature independent and interpreted as due to Pauli spin susceptibility. This categorizes the magnetic property as one that is insensitive to the atomic arrangement. The magnetic susceptibility has the constant values, 2.1 x 10 6 (emu/g) below the Ms and 3.0 x 10"6 (emu/g) above the As temperature. Between these two temperatures a plot of the data has a triangular form but as predicted, no difference is observed between those obtained from complete and incomplete cycles. 

Often the electronic spin mainly plays the indirect role through the Pauli principle, but in some cases it is directly the source of physical processes. Magnetism is an obvious example, and the combination of spin- and orbital moments determines the magnetic properties of materials. The theory must therefore be able to treat spin-polarization and SO-coupling simultaneously. This is therefore the third subject dealt with here. Magnetoelastic and magnetooptic effects are related to this and are discussed in Section 5. 

It is known that water molecules in PANl enhance the electrical conductivity several-fold [312]. Kahol el al. demonstrated that magnetic properties of PANl and its derivatives protonaled by HCI are affected by heat treatment to remove water molecules from the sample [2,313-315]. They found a conversion of the Pauli-like spins to the Curie spins upon heating below 100°C, causing removal of the water molecule from the polymer, and de-doping of HCI well above 100 C, resulting in a steep decrease in both the Pauli and Curie spins [313,314]. 

This prediction is a reasonable one for most cerium pnictides, namely CeP, CeAs, CeSb, and CeBi which, in fact, exhibit localized spin moments with an antiferromagnetic ordering of the 4/ electron remaining on each Ce [268]. CeN, however, is a metallic conductor with the corresponding magnetic properties and it only shows Pauli paramagnetism of the metallic electron gas, such that no local spin moment, characteristic for an unpaired electron, can be detected. This behavior leads to the possibility of an electronic formulation according to with one electron left in the conduction band, but... 

UTjSij with T=Co, Rh, Pt. Compounds of this class exhibit local moment behavior at high temperatures with sizable U moments (2.6-3.6)tB). The magnetic properties at low temperatures are varied, ranging from local moment ordered magnetism to Pauli paramagnetism. The intermetallics discussed here were measured by Dahnas de... 

Iron can assume the oxidation states+2, +3, and +6, the last being rare, and represented by only a few compounds, such as potassium ferrate, KaFeOj. The oxidation states +2 and +3 correspond to the ferrous ion, Fe ", and ferric ion, Fe, respectively. The ferrous ion has six electrons in the incomplete 2>d subshell, and the ferric ion has five electrons in this subshell. The magnetic properties of the compounds of iron and other transition elements are due to the presence of a smaller number of electrons in the 3td subshell than required to fill this subshell. For example, ferric ion can have all five of its 2>d electrons with spins oriented in the same direction, because there are five 2>d orbitals in the 3d subshell, and the Pauli principle permits parallel orientation of the spins of electrons so long as there is only one electron per orbital. The ferrous ion. is easily oxidized to ferric ion by air or other oxidizing agents. Both bipositive and terpositive iron form complexes, such as the ferrocyanide ion, Fe(CN)e and the ferricyanide ion, Fe(CN)e, but they do not form complexes with ammonia. 

Magnetic properties of the rest of the RNiSn compounds at 78-300 K were reported by Skolozdra et al. (1984b). The /(T) dependence of the RNiSn compounds, where R=Pr, Nd, Gd-Yb, follows the Curie-Weiss law. The stannides of Y, La, Lu are Pauli paramagnets. 

The magnetic properties of GdCuSn have been studied by Oesterreicher (1977). It was established that GdCuSn is an antiferromagnet with 7 n=24K. The X T) dependence of GdCuSn and the other RCuSn compounds (R= Ce-Nd, Gd-Tm) follows the Curie-Weiss law, while SmCuSn may be described by the modified Curie-Weiss law (Komarovskaya et al. 1983b). YCuSn, LaCuSn and LuCuSn are Pauli paramagnets (table 24). 

---