The uniform spin susceptibility χ around the quantum critical point is discussed on the basis of the mode-mode coupling theory of the antiferromagnetic (AF) spin fluctuations. The temperature dependence of χ around the quantum critical point reflects the magnetic-field dependence of the free energy due to that of the spin fluctuations. The results are χ ∝ 1 - β2t1/4 for the conventional class of AF fluctuations with the dynamical exponent z = 2, and χ ∝ 1 - β3t1/3 for a new class of AF fluctuations with z = 3, where t is the reduced temperature and β2 and β3 are numerical constants. For Ce7Ni3, the behavior of χ around the quantum critical point is possibly explaned by this theory with the conventional class of AF fluctuations with z = 2. The latter type of AF fluctuations with z = 3 is possible when the system contains even number of magnetic ions in the unit cell such as CeCu6-xAux (x = 0.1), because the AF ordering vector can coincide with one of the reciprocal lattice vectors.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)