Properties of MgCNi3 Superconductor

Abstract

The present invited article describes the properties of superconducting MgCN_i3 with T_c (ca.8 K) having a simple cubic perovskite structure with space group Pm-3m and lattice parameter a ca. 3.812 Å. Its conduction electrons are derived from the partially filled Ni d states that typically lead to the ferromagnetism in metallic Ni and many Ni-based binary alloys. It has electron type carriers in the normal state. The T_c increases with the increase of x in MgC_xN_i3 but generally decreases due to the Ni site doping by Co, Fe, Mn, Cu, etc. Again, the T_c is found to increase with the increase of external pressure. The electronic contribution is slightly higher than the lattice one in its normal state thermal conductivity. The specific heat and tunneling spectroscopic studies indicate that this is an s-wave BCS-type weak/moderate coupling type-II superconductor.