Weak-moment magnetism

Laves-phase compoimds can also be formed with 4d and 5d transition elements. To our knowledge, xSR studies were only carried out for CeRu2 (Huxley et al. 1996), which is considered a strongly correlated electron system. The case is discussed in sect. 9.3.1 ( xSR found weak moment magnetism). 

We have mentioned that the question posed above was answered in part by Shliomis and Stepanov [9]. They showed that for uniaxial particles, for weak applied magnetic fields, and in the noninertial limit, the equations of motion of the ferrofluid particle incorporating both the internal and the Brownian relaxation processes decouple from each other. Thus the reciprocal of the greatest relaxation time is the sum of the reciprocals of the Neel and Brownian relaxation times of both processes considered independently that is, those of a frozen Neel and a frozen Brownian mechanism In this instance the joint probability of the orientations of the magnetic moment and the particle in the fluid (i.e., the crystallographic axes) is the product of the individual probability distributions of the orientations of the axes and the particle so that the underlying Fokker Planck equation for the joint probability distribution also... 

In a weak external magnetic field B there will be a splitting of magnetic sublevels for the hyperfine structure (hfs) case as for the previously discussed case, where the influence of the nucleus was omitted. However, also in the hyperfine structure case the electronic shell is responsible for the interaction. Because of the coupling between I and J, these vectors pre-cess about F. Thus, the direction in relation to B of the electronic magnetic moment, which is associated with J, is influenced. The situation is illustrated in Fig. 2.19. 

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