Zero applied field

Fe(H20)6l and [Fe(H20)5Cl], the relaxation time in zero applied field will be longer than if all Fe " ions were in identical local environments [42]. 

Figure 6.44. Magnetization vs. temperature for a 100-bilayer LB film transferred with Mn+ with the measuring field applied parallel to the film plane, (a) Comparison of the data taken upon warming the film after cooling in zero applied field (ZFC) and cooling in a field of 1000 G (FC). For both cases, the measuring field is 100 G. (b) The difference in the FC and ZFC data showing a net magnetization below 11.5 0.5 K. M represents Reprinted with permission from Petruska et al, 2002. Copyright (2002) American Chemical Society.

Figure 11 Magnetization relaxation versus log(time) at 10 K in fields applied normal to a 0.7 /un-thick T Ca BaoCujOjQ superconducting film (Tc is 108 K). The solid triangles show relaxation due to flux creep out of the film in zero applied field after cooling in a 10 kOe field and removal of the field. The open triangles represent flux creep into the film in a S00 Oe field applied following zero field cooling. The dashed lines show the fit to Eq. (13).

In antiferromagnets, the neighboring spins are aligned antiparallel, there is no net macroscopic moment in zero applied field, and the susceptibility is anisotropic below the Neel temperature, TN. Most antiferromagnets are insulating solids (NiO and MnO, for example). 

Ferromagnets have their spins aligned parallel and exhibit large positive (about 102) magnetic susceptibilities. They possess a macroscopic spontaneous magnetization at zero applied field below the Curie temperature, Tc, and have a characteristic saturation moment, Ms, in a finite applied field (see Fig. 128). 

The parameters, IS and QS, shown in Table 5 are measured at 4.2 °K with zero applied field. The value of rj and the sign of QS are derived by matching computed spectra to the Mossbauer data for the oxidized proteins taken at 4.2 °K in 46 kilogauss applied magnetic field (Fig. 8). The above parameters do not exhibit any measurable temperature dependence over the temperature range from 4.2 °K to 77 °K. 

As added evidence for our confidence in the parameters shown in Table 6, the zero applied field spectra taken at low temperatures are shown in Fig. 13. Since the A-values for site 1 are almost isotropic, it is expected that the absorption peaks from this site would dominate the Mossbauer spectra in both zero and applied magnetic field. Comparison of Fig. 14 and Fig. 3 reveals that the absorption in these spectra at — 6 mm/S results from an isotropic hyperfine interaction of about —17 gauss at one of the iron sites in the reduced proteins. The anisotropic hyperfine interaction at site 2 results in a broad, unresolved absorption which accounts for the difference in shape between the spectra. 

Figure 6. Remanence enhancement in a two-phase Nd2Fe 4B/Fe3B magnet containing 343 grains. Left Finite element model of the grain structure. Right Magnetization distribution in a slice plane for zero applied field. The arrows denote the magnetization direction projected on a slice plane.

In ZFC scans, the sample is cooled in a zero applied field, and the magnetization is recorded as the temperature is increased in the presence of a... 

Fig. 72." Critical field He = (2//ex// )1/2 vs. temperature from antiferromagnetic resonance, (a) MnF2 Solid curve is Brillouin function for spin 5/2 and zero applied field normalized at only T = 0°K, Tn = 67.7°K. Triangles, circles, and...

If this expression were correct, M would be finite even in a zero-applied field. Lorentz s theory thus predicts that aU substances obeying the Curie law should be ferromagnetic at sufficiently low temperatures. Although this is not tme, Lorentz s theory did predict that spontaneous magnetization, in the absence of an externally applied field, was possible. 

In other words, the relaxation function of polarization is the normalized auto-correlation function of the polarization in thermal equilibrium in zero applied field. 

Figure 4. The energy levels of an Aviram and Ratner molecular rectifier [8]. a) Zero applied field, ground state configuration b) forward bias c) reverse bias (note that reverse > forward) d) reverse bias, alternative mechanism.

FIG. 1. Magnetization of a sample of nominal composition RbaCeo. The data labeled ZFC were obtained upon warming in a field of 2 Oe, after cooling the sample in zero applied field. The FC data were obtained by cooling the sample in 2 Oe, illustrating flux expulsion. 

For thermionic emission from a uniform surface, the saturation current density j extrapolated to zero applied field is given by... 

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