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

The intermetallic compound CeCoGe2.25Si0.75 has an antiferromagnetic transi tion at T-N = 5.5 K. Hydrostatic pressure decreases the Neel temperature an d drives this system to a quantum critical point (QCP). We characterize thi s 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 velocit y remains constant. We obtain the relevant magnetic parameters from the ele ctrical measurements and discuss the implications of our results within a m odel that emphasizes the importance of two-dimensional fluctuations.