Magnetization temperature dependence

Fig. 18 Field cooled (FCM), zero field cooled (ZFCM) and remnant (REM) magnetization temperature dependencies of [Mn(Cp )2][Ni(dsit)2]. From [53]...

Miller et al. [40] found that a compound obtained by the reaction of TPP-Mn(II) and tetracyanoethylene (TCNE) in toluene showed ferromagnetic behavior with magnetic temperature-dependent susceptibility, in which the Curie-Weiss temperature is 61 K. The structure (30) of the compound is considered as follows ... 

The saturation magnetization, J), is the (maximum) magnetic moment per unit of volume. It is easily derived from the spia configuration of the sublattices eight ionic moments and, hence, 40 ]1 per unit cell, which corresponds to = 668 mT at 0 K. This was the first experimental evidence for the Gorter model (66). The temperature dependence of J) (Fig. 7) is remarkable the — T curve is much less rounded than the usual BdUouia function (4). This results ia a relatively low J) value at RT (Table 2) and a relatively high (—0.2%/° C) temperature coefficient of J). By means of Mitssbauer spectroscopy, the temperature dependence of the separate sublattice contributions has been determined (68). It appears that the 12k sublattice is responsible for the unusual temperature dependence of the overall J). 

Fig. 9. Temperature dependences of the saturation magnetization AF, the coercivity FF and the Kerr rotation 9j for a 50-nm GdQ 24 0 oi o 75...

Results from magnetic susceptibiHty studies have been reported (50—53). Measurements (50) obtained by the Gouy method are shown in Figure 3. These are lower than those of other investigators. However, the temperature dependences of the magnetic susceptibiHties, for the various plutonium allotropes were similar. a-Plutonium single crystals show a slight anisotropy of (54). 

Fig. 5. Temperature dependence of the magnetic suseepli-bilities measured in a magnetic field of 2 T (a) Qo powder, (b) polycrystalline graphite anode, (c) gray-shell material, (d) buckybundle axis perpendicular to H, and (e) buckybundle axis parallel to H.

Fig. 6. The magnetic field dependence of the high- and low-temperature MR, respeetively the solid lines are caleulated. The inset shows a sehematic of the eontact eonfiguration for the transport measurements.

Song et al. [16] reported results relative to a four-point resistivity measurement on a large bundle of carbon nanotubes (60 um diameter and 350 tm in length between the two potential contacts). They explained their resistivity, magnetoresistance, and Hall effect results in terms of a conductor that could be modeled as a semimetal. Figures 4 (a) and (b) show the magnetic field dependence they observed on the high- and low-temperature MR, respectively. 

Fig. 10. Temperature dependence of the magnetic susceptibility of various carbon-based materials. The data on HOPG (H//c) are taken at 200 Oe. The data reported for nanolubes, graphite (H in-plane), and diamond, were taken at 4 kOe, those on diamond at 8 kOe. The ordinate axis is negative (after Heremans et al.[26 ).

Pauli spin susceptibility for the aligned CNTs has been measured and it is reported that the aligned CNTs are also metallic or semimetallic [30]. The temperature dependence of gn and gx s plotted in Fig. 5(a). Both values increase with decreasing temperature down to 40 K. A similar increase is observed for graphite. The g-value dependence on the angle 0 at 300 K is shown in Fig. 5(b) (inset). The g-value varies between gn = 2.0137 and gx= 2.0103 while the direction of magnetic fields changes from parallel to perpendicular to the tubes. These observed data fit well as... 

In Fig.. I we present the temperature dependence of the conductance for one of the CNTs, measured by means of a three-probe technique, in respectively zero magnetic field, 7 T and 14 T. The zero-field results showed a logarithmic decrease of the conductance at higher temperature, followed by a saturation of the conductance at very low temperature. At zero magnetic field the saturation occurs at a critical temperature, = 0.2 K, which shifts to higher temperatures in the presence of a magnetic field. 

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