Quantum critical point in CeCo(Ge1-xSix)3

The intermetallic compound CeCo(Ge1-xSix)(3) for x = 0, is an antiferromagnetic Kondo lattice system with a double magnetic transition at T-c = 21.2 K and T-N = 19 K. Upon doping with Si, these transitions merge into a single antiferromagnetic transition, as for the x = 0.75 composition studied here (T-N = 5.5 K). WC have applied hydrostatic pressure to this material and observed the vanishing of the antiferromagnetic transition as pressure increases, using electrical resistance and AC susceptibility measurements. For T much less than T-N, we show that the resistance is dominated by electron-magnon scattering. The magnon spectrum is characteristic of anisotropic antiferromagnets. The gap and stiffness of the spin waves, obtained from the fits of the resistance curves. vary with pressure. We discuss the behavior of these quantities close to the quantum critical point. (C) 2000 Elsevier Science B.V. All rights reserved.