Study of unconventional superconducting properties in noncentro symmetric superconductor using Andreev Reflection Point Contact (PCAR) spectroscopy

In a superconductor, the symmetry of the Cooper pair wave-function plays an important role in determining the properties of the superconducting state. When the crystal has inversion symmetry, the overall antisymmetry of the wave-function ensures either a spin-singlet or a spin-triplet pairing state. However, when the crystal structure does not have inversion symmetry, the presence of a spin-orbit interaction breaks the parity of the wave-function, resulting in admixture of a spin singlet and a spin triplet state. The discovery of the 1st non centrosymmetric superconductor, CePt3Si by Bauer et al in 2004 stimulated extensive research to understand the exotic properties of this kind of material.  In this talk, I will discuss about point contact spectroscopy study on a recently discovered non centrosymmetric superconductor, BiPd. Our point contact data gives clear evidence of multiple order parameters and clear signature of Andreev bound state associated for the triplet component of the order parameter for the first time in a non centrosymmetric superconductor.