Superconductivity

Non-centrosymmetric superconductor
Non-centrosymmetric structure causes a spontaneous eletcric field, leading to an interesting superconductivity.

The pressure-induced superconductor CeIrSi₃ crystallizes the tetragonal non-centrosymmetric structure. Without the mirror symmetry parallel to the c plane, conduction electrons interact with the spontaneous electric field along to the c axis by the asymmetric spin-orbital interaction, causing a rotational magnetic field perpendicular to the c axis. This characteric magnetic field splits the Fermi surface. The spins in each Fermi surface reversely turn round. The cooper pair consists of electrons in the same Fermi surface. However, the split Fermi surface disturbes the formation of normal cooper pair and theoretically leads to the mixing of singlet and triplet superconductivity. An another characteristic feature is a large upper critical field due to suppression of the paramagnetic effect, since the spin component is in the c plane.

Reflecting the non-centrosymmetric structure, CeIrSi₃ shows the characteristic superconducting properties under pressure, such as anisotropic upper critical field with a giant value parallel to c axis. Since the interesting superconductivity comes from not only structure and also strongly correlated 4f electron effect, we investigate non-4f La compounds.

Experiment of Superconductor
This is a demo movie using superconductor and strong magnet.