Large thermoelectric effect in ballistic Andreev interferometers

Employing quasiclassical theory of superconductivity combined with Keldysh technique we investigate large thermoelectric effect in multiterminal ballistic normal-superconducting hybrid structures. We argue that this effect is caused by electron-hole asymmetry generated by coherent Andreev reflection of quasiparticles at interfaces of two different superconductors with nonzero phase difference. Within our model we derive a general expression for thermoelectric voltages VT1,2 induced in two different normal terminals exposed to a thermal gradient. Our results apply at any temperature difference in the subgap regime and allow us to explicitly analyze both temperature and phase dependencies of VT1,2, demonstrating that in general there exists no fundamental relation between these voltages and the equilibrium Josephson current in superconducting-normal-superconducting junction.