Moment, small ordered magnetic

Regarding the very small ordered magnetic moment observed below the lower superconducting transition, one might think of four possibilities that are immediately at hand ... 

Figure 23 Magnetic structures of the phosphides AC02P2 (A = Ca, Sr, La, Ce, Pr, Nd, Eu). The cobalt atoms (small circles) with their ordered magnetic moments are shown together with the A atoms (large circles), which are in the positions tO 0 Ot ana n /o 1 ni n r tn body-centered nuclear cell (from Reehuis et ) o e...

Antiferromagnetism - A type of magnetism in which the magnetic moments of atoms in a solid are ordered into two anti-paraUel aligned sublattices. Antiferromagnets are characterized by a zero or small positive magnetic susceptibility. The... 

Susceptibihty, resistivity and specific heat measurements (see Amoretti et al. 1992), as well as Mossbauer spectroscopy (Friedt et al. 1985) on Np02 establish a transition at 25 K. Its exact nature has, however, been enigmatic, especially since neither neutron (Caciuffo et al. 1987) nor Mossbauer data (see Dunlap and Kalvius 1985) could prove the existence of an ordered magnetic state. In fact, the Mossbauer spectra for J < 25K are not incompatible with the presence of magnetic order (Dunlap et al. 1968) but if so, require that the moment on the Np ion be extremely small (< O.Olfis). Friedt et al. (1985) concluded that the transition is more likely to be structural. Similarly the behavior of the... 

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