Resistivity magnetic field dependence

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. 16. Magnetic field dependence of the resistivity for a 200-nm thick film of Ga Mn.t As with x = 0.053 in the high-temperature paramagnetic region. The solid lines show the fitting using eq. (2) (Omiya et al. 2000).

Fig. 19. Magnetic field dependence of the diagonal resistivity p (open circles) and magnetization Afnaii (close circles) determined from the ratio of the Hall and diagonal resistivities, Afnall = PHM/CP< where c = 6.3, for a 1.3-rrm thick film of lni tMnr As with x = 0.013. The solid line is a fit by the modified Brillouin function B (y), where S = 5/2 and y = SgpgB/(T + T0) with T0 = 1.5 K. The inset shows the hysteresis observed in the Hall resistivity at 3.5 K (Ohno et al. 1992).

Figure IV 2 9. Magnetic field dependence of the Josephson flux-flow resistance, Rg, at different temperatures with fits to Eq. (7) [17]...

Fig. 11.16. The magnetic field dependence of the Hall resistivity ph (solid circles) and magnetization M (line) at T = 300K. The inset plots extraordinary Hall coefficient it, at T = 77K [46],...

The second effect, the rapid or fast oscillations, also briefly mentioned in Sect. 2.2.3, shows many similarities to the usual SdH effect and was, therefore, in the beginning interpreted as being due to closed orbits in the DW state. However, as pointed out already, the resistance oscillations, although periodic in 1/5, show a temperature and magnetic field dependence which is not understandable within the usual Lifshitz-Kosevich theory (3.6). 

As an example of rapid oscillations Fig. 4.1 shows the magnetic field dependence of the relative resistivity of (TMTSF)2N03 for different temperatures [92]. The periodicity of two sets of oscillations in 1/5 is clearly visible. However, the oscillations are largest for 4.2 K and are reduced both for higher and lower temperatures. A similar inconsistency with the predictions of (3.6)... 

The synthesis of macroscopic amounts of C o and C70 (fullerenes) has stimuiated a variety of studies on their chemical and physical properties. We recently demonstrated that C o and C70 become conductive when doped with alkali metals. Here we describe iow-temperature studies of potassium-doped both as films and bulk samples, and demonstrate that this material becomes superconducting, Superconductivity is demonstrated by microwave, resistivity and Melssner-effect measurements. Both polycrystalline powders and thin-flim samples were studied. A thin film showed a resistance transition with an onset temperature of 16 K and essentially zero resistance near 5 K. Bulk samples showed a well-defined Meissner effect and magnetic-field-dependent microwave absorption beginning at 18 K. The onset of superconductivity at 18 K is the highest yet observed for a molecular superconductor. 

Fig. 12.18. Resistivity (a) and (b) vs. temperature in the [010] and [001] directions of the aligned a-axis film. The Jc of a two-domain a-axis film and a c-axis film are shown for comparison. The inset of (b) shows the magnetic field dependence of the normalized in the two directions at 77 K compared with a high-/c c-axis film which is known to not be weak-link limited. The scaled field is in kG for the c-axis film and in kG/(mass ratio) for the aligned a-axis film.

Fig. 95. Properties of holmium ethylsulphate. (a) The magnetic field dependence of the thermal resistivity, (b) Dependence of the energy levels on magnetic field, (c, d, e) Schemes of contributions of different parts of the phonon spectrum to c, (maxima of curves are near hm T).

Fig. 65. Temperature and magnetic field dependence of the electrical resistivity of Tm,Se. (After Batlogg et al. 1977.)...

FIGURE 116 Resistivity of CePtSi2 with a magnetic field up to 0.7 T under 1.7 GPa. Inset (A) Magnetic field dependence of at 1.7 and 1.8 GPa evaluated from resistivity and ac susceptibility, respectively. Inset (B) Temperature dependence of Xx for CePtSij under 1.8 GPa in various magnetic fields (Nakano et al., 2009a). 

Electrical resistivity measurements on CeSb and CeBi single crystals are displayed in fig. 123 (Suzuki et al. 1981). For CeSb a sharp decrease of p versus T is observed at Tn (16.5 K), indicating a first-order magnetic transition. A shallow minimum follows around 80 K. Subtracting Pph(T), determined from the isostructural LaSb compound, reveals that p g is proportional to — In T, which is typical for a Kondo lattice (Kasuya et al. 1982). The magnetic-field dependence of the electrical resistivity of CeSb at various temperatures is given in fig. 124. 

Figure 4.27 (a) Isothermal magnetic field dependent resistivity of CuCro.96Mgo.04 O2 and (b) enlargement of the S T) curves for the same compound collected upon cooling from 315 K in 0 T and then in 9 T... 

The localization length can be estimated from the expression for the weak magnetic field dependence of the VRH resistivity [122.179] ... 

Fig. 2.45 The magnetic field dependence of the resistivity. In [p(//)/p(0)j vs. H- for PPy-Pp6 samples in the insulating regime. The localization length was calculated from the slope (solid line) using Eq. (23).

This localization gives rise to non-classical effects which are manifested both in the temperature and the magnetic-field dependences of the electrical resistivity at low temperature. The resistivity value goes through a minimum, then increases logarithmically, while the magnetoresistance is negative [478],... 

E = applied voltage, V V = counterelectromotive force (generated voltage), V R = armature resistance, H I = armature current, A k = constant dependent on motor design n = speed, r/min ( ) = magnetic-field flux... 

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