Huge upper critical field in the superconductor with non-centrosymmetric crystal structure CeCoGe3

We report the upper critical field, H-c2 of the non-centrosymmetric compound CeCoGe3 by resistivity measurements under high pressure of 7.1 GPa, for H along c and a axis, and for a magnetic field up to 17T. H-c2 is very anisotropic, saturating at low temperature for H along the a axis and linear for H along the c axis. Very high H-c2(T) is observed for H along the c axis, with a huge value of the slope dH(c2)/dT = -47 +/- 1.3 T/K, the highest ever reported if normalized to the superconducting temperature of 0.65 K. This is most probably related to a conjunction of a heavy fermionic state and the absence of the Pauli limitation. A fit of H-c2(7) shows that the curves for a and c axis can be reproduced with a moderate coupling Eliashberg theory. (C) 2009 Elsevier B.V. All rights reserved.