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.