Evidence for an antiferromagnetic quantum critical point near stoichiometric CeCu2Si2

We report on a comparative study of the electrical resistivity, rho, and specific heat, C, on the presumably magnetically ordered phase A in near stoichiometric CeCu2Si2 at very low-T, in magnetic fields and as a function of pressure. Our data indicate the formation of a spin-density-wave (SDW) phase below T-A. Phase A depends sensitively on the strength g of hybridisation between 4f- and conduction electrons and g can be varied by the application of pressure or suitable changes in composition. Our results suggest a continuous evolution T-A --> 0 for g --> g(c). Hydrostatic-pressure experiments on a near stoichiometric polycrystal prove that g(c) marks a quantum critical point of antiferromagnetic type consistent with the SDW-nature of phase A. (C) 1999 Elsevier Science B.V. All rights reserved.