Magnetic field dependence of the low-temperature specific heat of MgCNi3

Abstract

The specific heat of a superconductor carries crucial signatures of its order parameter. The newly discovered superconductor MgCNi3 is predicted to be unstable to ferromagnetism, and the symmetry of its order parameter symmetry is of current interest. To shed light on this issue, we have measured the low-temperature specific heat of MgCNi3 in H. Careful analysis of the data suggests that gamma(H) proportional to H. Together with other physical properties, the results imply that MgCNi3 is a moderate-coupling BCS superconductor. (C) 2003 Elsevier Science B.V. All rights reserved.