Abstract :

In the first part of my talk, I will focus on the transformation of conventional even-ω to unconventional odd-ω superconductivity in a Josephson junction made up of Weyl nodal loop semimetal and two conventional s-wave superconductors. Weyl nodal loop semimetal (WNLS) is characterized by the nodal loop Fermi surface and drumhead-like surface states (DSS). Due to the strong spin-polarization of DSS, odd-ω spin-triplet pairing of equal spin is induced on the surface of WNLS and it dominates over all other pairings, including the spin-singlet even-ω type, throughout the surface. It is also possible to induce unequal spin-triplet odd-ω pairing states in the presence of a ferromagnet placed on the top of WNLS. However, the amplitudes of the induced pairings are sensitive to the polarization of the ferromagent and it is anisotropic with respect to the orientation of the polarization vector. The signatures of the different odd-ω pairings and DSS are captured in the behavior of the Josephson current through the semimetal. The effect of ferromagnetism on the current will be discussed as well.
In the second part, I will discuss the effect of interfacial Rashba spin-orbit interaction in the thermoelectric properties of a ferromagent-superconductor (FS) hybrid junction. The behavior of thermal conductance with temperature manifests a cross-over temperature scale separating two different regimes corresponding to the opposite behavior with respect to the polarization of the ferromagent. I will show that interplay of Rashba, barrier potential and the polarization may enhance the Seebeck coefficient as well as thermoelectric figure of merit considerably elevating the potential of the FS junction as a thermoelectric device.