Abstract
The usually negligibly small thermoelectric effects in superconducting heterostructures can be boosted dramatically due to the simultaneous effect of spin splitting and spin filtering. Building on an idea of our earlier work (Machon et al 2013 Phys. Rev. Lett. 110 047002), we propose realistic mesoscopic setups to observe thermoelectric effects in superconductor heterostructures with ferromagnetic interfaces or terminals. We focus on the Seebeck effect being a direct measure of the local thermoelectric response and find that a thermopower of the order of can be achieved in a transistor-like structure. A measurement of the thermopower can furthermore be used to determine quantitatively the spin-dependent interface parameters that induce the spin splitting. For applications in nanoscale cooling we discuss the figure of merit for which we find values exceeding 1.5 for temperatures K.
Highlights
Since their discovery at the beginning of the 19th century [1, 2, 3, 4], thermoelectric effects have attracted continued attention in physics, as they provide the basis for a large variety of devices used in a multitude of fields in physics and engineering connected with energy management on the nano-scale
We have pointed out the possibility to generate large local and nonlocal thermoelectric effects [59] in heterostructures of ferromagnets and superconductors by the combined effect of induced spin splitting and spin-polarized transport
Further works studied the thermoelectric effect related to impurities in bulk superconductors [62, 63] or to magnetic field or interface induced spin splitting in tunnel junctions [64, 65]
Summary
Its distribution functions and spectral functions will be determined self-consistently by the procedure described below It is the place where the spin-polarization of the pair amplitudes takes place via the spin-dependent reflection phases at the ferromagnetic interfaces. In the effective two-terminal case an additional normal (or ferromagnetic) conductor is coupled to the node (G2), and we assume here that the two contacts are identical (G1 = G2). The spin-dependent scattering phases at the interface give rise to an induced exchange field in the node which is proximity coupled to the superconductor. This effect is quantified by a conductance parameter Gφc, arising from spin-dependent phase shifts in the reflection amplitudes at the ferromagnetic contacts of the node. The suggested experimental setup is only one possible realization
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