Superconductivity in MgCNi3

 

Sung-Ik Lee, Sogang University

 

In spite of the large number of ferromagnetic Ni atoms in its unit cell, MgCNi3 shows superconductivity rather than Magnetism. According to band-structure calculations, MgCNi3 is near a ferromagnetic instability due to the high density of states at the Fermi level. However, whether or not the ferromagnetism in the formation of spin fluctuation remains is still unclear. The magnetism in the superconductivity can result in spin-triplet superconductivity or spin-affected conductivity. Moreover, the superconducting origin of this material has not yet been clearly identified, and the experimental results are still conflicting. For example, both s and non-s wave gap symmetry were observed by using various experimental tools. Recently we successfully synthesized the MgCNi3 single crystals and measured transport, penetration depth, tunneling and specific heat and clear the above issues. The origin of the superconductivity is from the electron-phonon interaction and gap symmetry is s-wave. Various issues will be discussed.