Magnetism Pauli susceptibility

Although it is required to refine the above condition I in actuality, this rather simple but impressive prediction seems to have much stimulated the experiments on the electrical-conductivity measurement and the related solid-state properties in spite of technological difficulties in purification of the CNT sample and in direct measurement of its electrical conductivity (see Chap. 10). For instance, for MWCNT, a direct conductivity measurement has proved the existence of metallic sample [7]. The electron spin resonance (ESR) (see Chap. 8) [8] and the C nuclear magnetic resonance (NMR) [9] measurements have also proved that MWCNT can show metallic property based on the Pauli susceptibility and Korringa-like relation, respectively. On the other hand, existence of semiconductive MWCNT sample has also been shown by the ESR measurement [ 10], For SWCNT, a combination of direct electrical conductivity and the ESR measurements has confirmed the metallic property of the sample employed therein [11]. More recently, bandgap values of several SWCNT... 

Electron spin resonance (ESR) is extensively used in the study of fulleride ions, as the magnetic characterization of these molecular ions yields fundamental information on the electronic structure. An ESR signal can in principle appear in any system containing fulleride ions, as the configuration can involve unpaired spins even in systems with an even number of electrons. In solids, the Pauli susceptibility indicates a metallic state. 

The paramagnetism of the conduction electrons, not observable by ESR, can however be detected by a measurement of the magnetic susceptibility. In the region of metalhc conductivity, one observes in the contribution of the conduction electrons a nearly temperature-independent Pauli susceptibility, well known from metals. In those crystals which undergo a Peierls transition and become semiconductors or insulators at low temperatures, the Pauli susceptibility is transformed into a Curie-law behaviour. The susceptibility then increases with further decreasing tern-... 

The intercalation of graphite with large organic systems has been investigated. Numerous physical properties still need to be investigated, including thin-film resistivity, and magnetic susceptibility probes of the Pauli susceptibility of these materials. 

The magnetic susceptibility was first measured as a function of protonation for the Class I family of materials [12]. Results showed a quasi-linear increase in Pauli susceptibility, which led to the proposal of the formation of metalHc islands of the emeraldine salt in the emeraldine base form with protonation. X-ray diffraction studies of the ES-I series, as a function of protonation, gives a quasi-linear increase in the crystalline salt fraction with protonation, supporting the formation of crystalline metallic islands with increasing protonation level. Electron spin resonance studies of the Class II materials, as a function of protonation level, show a dramatically different behavior [20]. Initial protonation of the base EB-II leads to a spinless material, until compositions are achieved, such that essentially all of the amorphous regions are fully doped. At that point, there is an increase in the Pauli susceptibility, corresponding to the formation of crystalline ES-II (Fig. 7). Preliminary studies show that the Pauli susceptibility is essentially the same for the ES- and ES-II structures. 

All samples show a nearly temperature-independent magnetic susceptibility down to 50 K. Below 50 K, a temperature-dependent Curie-like susceptibility is observed. Figure 1.16 shows the y vs. 1/T plots for unblended PAni and PAni-PMMA blends. The temperature-independent Pauli susceptibility is calculated from the above plot, and the density of the states at the Fermi energy is calculated. 

Pauli Susceptibility paramagnetic, approximately temperature independent magnetic susceptibility due to conduction electrons. The Pauli susceptibility, = 2p N Ef), where is a Bohr magneton and N E ) is the density of states at the Fermi level. 

Pauli susceptibility susceptibility for magnetic field applied in -direction magnon frequency cyclotron frequency (eBIm )... 

X (T = 0) is apparently considerably enhanced above the Pauli susceptibility Ap = 2(gMB)V( p) = 2.4 X 10 p.bT calculated from Keeton and Loucks (1968) estimate of the density of states at the Fermi level. However, a note of caution needs to be injected into these estimates of the conduction electron susceptibility. It is apparent from figs. 6.1 and 6.2 that some 10 to 15 T are required to complete the magnetization process by overcoming residusd domain walls and the effects of crystal imperfections. Measurements of the high-field susceptibility... 

As cast emeraldine films (obtained from a solution of emeraldine base in A-methyl pyrrolidone NMP) are diamagnetic due to the absence of a charge carrier, unlike this film on doping shows paramagnetism. The total magnetic susceptibility of this film on doping shows paramagnetism and this is due to temperature-independent Pauli susceptibility and temperature-dependent Curie susceptibility. 

In normal metals the Pauli susceptibility is constant with temperature, but in normal metals we are dealing with bandwidths in the order of eV and the density of states is practically constant near the Fermi level. In heavy fermions the density of states changes very rapidly with energy which produces drastic effects in the temperature dependence of the susceptibility. The formulae which we adopt for the derivation of the Pauli susceptibility are eqs. (17-19) where the int ral in eq. (18) is the well known expression of the Pauli magnetization. When a peak in the density of states occurs at the Fermi level, this term shows a Curie-Weiss dependence with temperature and the susceptibility decreases more rapidly as the peak is enhanced and the bandwidth is reduced. We can also explain the susceptibility of heavy fermions in different, simpler terms. With Eji = and the carrier concentration N being... 

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