Magnetic heat capacity interaction

The excess (magnetic) heat capacity may be represented to a good approximation as the sum of (a) the electronic transitional (or Schottky) heat capacity, (b) the effects of interaction between the electrons and the nuclear spin of the paramagnetic ion, (c) the dipolar interaction between these ions, and (d) interactions for other types of interionic coupling. The last three terms are often small above 2°K. and in some instances can be obtained from paramagnetic relaxation data. In principle, the second and third can also be obtained from paramagnetic resonance data. 

NdRu4Sbi2 is metallic and undergoes some type of magnetic transition near 1.3 K. The magnetic susceptibility follows a Curie-Weiss law above 50 K with an effective moment of 3.45/u.b and a Weiss temperature of -28 K. Crystal fields likely effect the susceptibility and magnetic interactions for temperatures below 50 K. Low temperature heat capacity data confirm the bulk nature of the magnetic transition (Takeda and Ishikawa, 2000b). 

A nuclear contribution to the heat capacity arises from the two isotopes " Nd and " Nd. Heat capacity measurements by Anderson et al. (1969) (0.026-0.37 K) were used to derive values of the magnetic interaction parameters (a ) and the quadrupole coupling constants (P) for both isotopes and following the procedure as given in Section 2.4, and in Part 8.11, the variation with temperature of the nuclear contribution was derived. 

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