Quaternary Borocarbides

Anisotropic superconducting energy gaps is normally believed to be associated with the unconventional pairing mechanisms of non-phononic origin such as pairing mediated by ferromagnetic or antiferromagnetic spin fluctuations. Our interests in recent years has been on the study of a relatively less studied class of anisotropic superconductors where large gap anisotropy arises from a different origin, namely, the multiband nature of the Fermi surface. Our model system for these studies has been the quaternary borocarbide superconductor YNi2B2C which was discovered in this institute in 1994. The peculiarity of this system is the existence of very slow and very fast electrons on the Fermi surface at different k directions. Using directional Point Contact Spectroscopy we could demonstrate that the large gap anisotropy in this material arises from the difference is coupling strengths of these slow and fast electrons to the crystalline lattice. Our current emphasis in this area is on the study of impurity scattering on the multiband nature of superconductivity as well as exploration of novel systems such as Lu5Ir4Si10 where the same mechanism is likely to give rise to large gap anisotropy.

(To see our publications in this area go to the publications page)

Some more details can be found here:

Disordered Superconductors

Nanostructured Superconductors

Spin Polarization Measurements using PCAR