Correlation length, magnetic

Equation 5 demonstrates the T divergence of the susceptibility and the occurrence of a critical point at T = 0 K. finally, it should be mentioned that the magnetic correlation length, can also be introduced in an equivalent form of the Eq. 5 ... 

Fig. 49. Magnetic correlation lengths along the a- and c-directions as a function of temperature for CeCu (Rossat-Mignod et al. 1988). Lines through data points are guides to the eye.

Fig. 8. Inverse magnetic correlation length for antiferromagnetic spin fluctuations in lightly doped La2, Sr,Cu04. The lines are based on a simple model in which the zero-temperature limit of K is governed by the doping, and the temperature dependence is derived from the renormalized classical expression (eq. 5). From Keimer et al. (1992).

A similar rise in the small angle scattering is also seen in the three Natpe Ni samples which also shows OZ behaviour (Fig. 6.11). The correlation lengths are shown in Table 6.8. Although, based on the above discussion of iron, some caution should be used in quantitative interpretation, it is clear that there are still significant magnetic correlations, possibly even greater in size than in iron. This is somewhat unexpected, as the temperatures at which these samples were measured are very far from the Invar Curie temperature [4] of -500 K. A comparable situation is seen in Ni where the Curie temperature is 631 K [33]. However... 

NSE neutron spin echo K inverse magnetic correlation length... 

Mossbauer spectroscopy, hence the magnetic correlation length is expected to be larger than the SRO-range. 

Bohr magneton unit of dipole moment 9.2741 xlO joule/tesla real space magnetic correlation length or superconducting coherence length... 

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