Thermoelectric response of Josephson junction: from ballistic to disordered

Abstract

It is known that Josephson junction (JJ) hosting scattering centers with energy dependent scattering amplitudes which breaks the ω → −ω symmetry (where ω is the excitation energy of electron about the Fermi level) exhibits finite thermoelectric response. In contrast, here we show that even in a ballistic JJ this symmetry is broken and it leads to a non-zero thermoelectric response when the junction length is of the order of coherence length of the superconductor and the corresponding thermoelectric coefficient confirms to the universal sinusoidal dependence on φ12, where φ12 is the superconducting phase bias. In presence of multiple scatterers in the junction region, we have numerically shown that the sign of the even-in-φ12 part of the thermoelectric coefficient fluctuates violently from one disorder configuration to another hence averaging to vanishingly small values while the odd part tends towards the universal sinusoidal dependence on φ12 as we approach the large disorder limit under disorder averaging.

Phase-control of bipolar thermoelectricity in Josephson tunnel junctions

“…In fact, superconducting-based platforms also represent valuable resources for heat management purposes [7] including on-chip cooling [8] and phase-coherent modulation of heat currents [9]. Recently, superconductors have been strongly reconsidered for thermoelectricity [10][11][12][13][14][15][16][17][18], i.e., for the direct conversion of a thermal gradient into an electrical power. At a first glance, thermoelectric effects and the superconducting state are competing for different reasons.…”

“…This potentiality has been exploited in hybrid superconductingferromagnetic insulator tunnel junctions, where the combination of the spin-filtering and the spin-splitting of the BCS superconducting DoS explicitly breaks the PH symmetry, leading to strong thermoelectricity [11,12,24], thermophase [25] effects and nonreciprocal IV characteristics. Other strategies include the identification of non-local effects [10,12,14,17,[26][27][28][29][30] and/or the use of topological materials [16,18,[31][32][33]. Few years ago, thermoelectricity was theoretically predicted in a superconductor-insulator-superconductor (S 1 IS 2 ) tunnel junction with different superconducting zero-temperature energy gaps (∆ 0,1 > ∆ 0,2 ) and vanishing Josephson coupling [34,35].…”