A quantum critical point of the heavy fermion $\mathrm{Ce}({\mathrm{Ru}}_{1-x}{\mathrm{Rh}}_x{)}_2{\mathrm{Si}}_2$, $(x=0,0.03)$ has been studied by single-crystalline neutron scattering. By accurately measuring the dynamical susceptibility at the antiferromagnetic wave vector ${\mathit{k}}_3=0.35{\mathit{c}}^{*}$, we have shown that the inverse energy width $\Gamma ({\mathit{k}}_3)$, i.e., the inverse correlation time, depends on temperature as $\Gamma ({\mathit{k}}_3)=c_1+c_2{T}^{3/2\pm 0.1}$, where $c_1$ and $c_2$ are $x$ dependent constants, in a low temperature range. This critical exponent $3/2\pm 0.1$ proves that the quantum critical point is controlled by that of the itinerant antiferromagnet.

• Received 23 April 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.016401