Spin susceptibility properties

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. 

Fig. 4. The concentration dependence of various electronic properties of metal-ammonia solutions, (a) The ratio of electrical conductivity to the concentration of metal-equivalent conductance, as a function of metal concentration (240 K). [Data from Kraus (111).] (b) The molar spin (O) and static ( ) susceptibilities of sodium-ammonia solutions at 240 K. Data of Hutchison and Pastor (spin, Ref. 98) and Huster (static, Ref. 97), as given in Cohen and Thompson (37). The spin susceptibility is calculated at 240 K for an assembly of noninteracting electrons, including degeneracy when required (37).

For both systems the temperature dependence of the spin susceptibility is about similar, with a 40% monotonous drop from 300 K to 50 K [37,38]. Clearly, there is no close relation between transport and magnetic properties in the high-7 regime of these salts. This is an experimental illustration of the spin-charge separation concept of one-dimensional conductors. 

Very little is known about the physical properties of carbon onions. Electron spin resonance measurements on macroscopic quantities of onions, with 3-10 nm sizes, show that these structures have a Pauli-like spin susceptibility close to that of graphite [181]. It demonstrates that carbon onions also belong to the family of conducting carbon structures. 

The discovery 5 th when in solution in concentrated sulfuric acid, poly aniline is in the protonated form, [B-NH-B-NH-]+ n, and that it is recovered as the partially crystalline salt, [B-NH-B-NH-]+ n(HS04 )n, from solutions in sulfuric acid O y precipitation in water or methanol) has opened the way to a more complete characterization of the polymer, and to studies directed toward the determination of the intrinsic properties of the ordered material. For example, the temperature independence of the spin susceptibility of the more highly ordered crystalline material above 125K is consistent with the Pauli spin susceptibility expected for a metal,with a density of states at the Fermi level estimated as 1 state per eV per formula unit (two rings). 

There are few reports of thermal property measurements (e.g., thermal conductivity, specific heat, etc.) [52, 53]. The linear term in specific heat at low temperatures is evidence of the continuous density of states with a well-defined Fermi energy for any metallic system. The low temperature specific heat, C, for a metallic PPy-PFg sample and for an insulating PPy-p-toluenesulfonate (TSO) sample is shown in Figure 2.13 [54]. The data for both samples fit to the equation C/T = y+ jS P, where yand P are the electronic and lattice contributions, respectively. From the values of P and y, the calculated density of states for metallic and insulating samples are 3.6 0.12 and 1.2 0.04 states per eV per unit, and the corresponding Debye temperatures are 210 7 and 191 6.3 K, respectively. These values are comparable to those obtained from the spin susceptibility data. 

In Part I- F the magnetic properties of metal-ammonia solutions were listed. As we have seen, the obseiwed magnetic properties consisted of results of total susceptibility measurements, spin susceptibility measurements using electron spin resonance techniques, dynamic features of electron spin resonance involving measurements on the relaxation times, and nuclear resonance studies. We shall first take up the explanation of the susceptibility data using the cavity, cluster, and unified models and subsequently consider the interpretation of the results of resonance studies. 

In a recent study von Molnar et al. (1982) present a comparison of random-anisotropy and spin-glass properties in the amorphous rare-earth alloys a-Dyo.52Cuo.48 (T>//o large), a-Gd jAgo 4 (DZ/q small), and a-Gdo.j Alo (a well known spin glass). This work has also been stimulated by the theoretical prediction of Aharony and Pytte (1980) of an infinite-susceptibility phase . Detailed measurements of the magnetization as a function of temperature and... 

In this Section we try to understand the INS and NMR experiments on the basis of the SRI SB mean-field theory. Using a generalized RPA expression for the spin susceptibility and assuming that the AFM correlations are spatially filtered by various -dependent hyperfine form factors, we focus, in particular, on the spin dynamical properties in the paraphase of the t-t -J model. Our starting point is an RPA-like form for the exchange-enhanced spin susceptibility [5, 6, 65]... 

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