Bipolar Thermoelectric Josephson Engine [article]

Gaia Germanese, Federico Paolucci, Giampiero Marchegiani, Alessandro Braggio, Francesco Giazotto
<span title="2022-02-09">2022</span> <i > arXiv </i> &nbsp; <span class="release-stage" >pre-print</span>
Thermoelectric effects in metals are typically small due to the nearly-perfect particle-hole (PH) symmetry around their Fermi surface [1, 2]. Despite being initially considered paradoxical [3], thermophase effects [4-8] and linear thermoelectricity [9] in superconducting systems were identified only when PH symmetry is explicitly broken [10-14]. Here, we experimentally demonstrate that a superconducting tunnel junction can develop a very large bipolar thermoelectric effect in the presence of a
more &raquo; ... onlinear thermal gradient thanks to spontaneous PH symmetry breaking [15]. Our junctions show a maximum thermovoltage of ±150 μ V at ±650 mK, directly proportional to the superconducting gap. Notably, the corresponding Seebeck coefficient of ±300 μV/K is roughly 10^5 times larger than the one expected for a normal metal at the same temperature [16, 17]. Moreover, by integrating our junctions into a Josephson interferometer, we realize a bipolar thermoelectric Josephson engine (BTJE) [18] with phase-coherent thermopower control [19]. When connected to a generic load, the BTJE generates a phase-tunable electric power up to about 140 mW/m^2 at subKelvin temperatures. In addition, our device implements the prototype for a persistent thermoelectric memory cell, written or erased by current injection [20]. We expect that our findings will trigger thermoelectricity in PH symmetric systems, and will lead to a number of groundbreaking applications in superconducting electronics [21], cutting-edge quantum technologies [22-24] and sensing [25].
<span class="external-identifiers"> <a target="_blank" rel="external noopener" href="">arXiv:2202.02121v2</a> <a target="_blank" rel="external noopener" href="">fatcat:f234vp64cvb73oyo5na3wobcbe</a> </span>
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