Anisotropic quantum critical behavior in CeCoGe3-xSix -: art. no. 012404

The intermetallic compound CeCoGe2.25Si0.75 has an antiferromagnetic transition at T-N = 5.5 K. Hydrostatic pressure decreases the Neel temperature and drives this system to a quantum critical point (QCP). We characterize this approach to the QCP using electrical resistivity measurements. For T<T-N the resistivity is dominated by electron-magnon scattering and this allows to obtain the pressure variation of the spin-wave gap and of the spin-wave velocity. We find that for a significant range of pressure close to the QCP, the Sap and the Neel temperature decrease with pressure while the velocity remains constant. We obtain the relevant magnetic parameters from the electrical measurements and discuss the implications of our results within a model that emphasizes the importance of two-dimensional fluctuations.