Condensed Matter Physics Seminar: Tomas Löfwander

Abstract

In an unconventional superconductor, the interplay of scattering off impurities and Andreev processes may lead to different scattering times for electronlike and holelike quasiparticles. Such electron-hole asymmetry appears when the impurity scattering phase shift is intermediate between the Born and unitary limits and leads to an expectation for large thermoelectric effects. Here, we examine the thermoelectric response of a d-wave superconductor connected to normal-metal reservoirs under a temperature bias using a fully self-consistent quasiclassical theory. The thermoelectrically induced quasiparticle current is cancelled by superflow in an open circuit setup, but at the cost of a charge imbalance induced at the contacts and extending across the structure. For a semiballistic superconductor with good contacts, we find thermopowers of order several μV/K, suggesting a thermovoltage measurement as a promising path to investigate thermoelectricity in unconventional superconductors.

The presentation is based on a series of recent papers [1-4], in particular Ref. [2].

[1] K.M. Seja and T.L., Phys. Rev. B 104, 104502 (2021)
[2] K.M. Seja, L. Jacob, and T.L., Phys. Rev. B 105, 104506 (2022)
[3] K.M. Seja and T.L., J. Phys.: Condens. Matter 34 425301 (2022)
[4] K.M. Seja and T.L., Phys. Rev. B 106, 144511 (2022)