Upper critical field of CeCu2Si2 at very high pressure

Superconducting and normal properties of a high quality single crystal of CeCu2Si2 have been investigated by resistivity measurements under pressure up to 10 GPa and in magnetic fields up to 8 T. From the initial slope H-c2' of the upper critical field and the low temperature resistivity behaviour (rho proportional to AT(2)) there is a qualitative agreement for the pressure-induced decrease of the quasi-particle effective mass m* up to 4.5 GPa. At higher pressure however, the coefficient A drops by about two orders of magnitude without any corresponding effect in H-c2'. A preliminary fit was made to the upper critical field with a model including both Pauli and orbital limitations assuming either weak or strong coupling in the clean and dirty limits. (C) 1998 Elsevier Science Ltd. All rights reserved.