Quantum critical point of an itinerant antiferromagnet in a heavy fermion

A quantum critical point of the heavy fermion Ce(Ru1-xRhx)(2)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 k(3)=0.35c(*), we have shown that the inverse energy width Gamma(k(3)), i.e., the inverse correlation time, depends on temperature as Gamma(k(3))=c(1)+c(2)T(3/2 +/- 0.1), where c(1) and c(2) are x dependent constants, in a low temperature range. This critical exponent 3/2 +/- 0.1 proves that the quantum critical point is controlled by that of the itinerant antiferromagnet.