PhD Thesis Defense | Alberto Hijano Mendizabal

Non-equilibrium properties of superconducting structures in the presence of spin-dependent fields

February 23, 11:00

Informatics Faculty Auditorium

Candidate: Alberto Hijano Mendizabal

Supervisors:  F. Sebastián Bergeret Sbarbaro and José María Pitarke de la Torre

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Summary

Extensive theoretical and experimental works highlight the versatility of hybrid superconducting structures. They find applications in diverse domains such as spintronics, thermoelectricity, and sensors. Most of these applications are based on the non-equilibrium properties of superconductors, i.e., properties that arise out of thermodynamic equilibrium. In this thesis we study the non-equilibrium properties of superconductors in the presence of spin-dependent fields, that is, fields that interact with the spin of quasiparticles, such as Zeeman fields and spin-orbit coupling. Specifically, we study the charge, thermoelectric and spintronic transport in several superconducting hybrid devices.

Figure 1. Simple circuit scheme of photon-assisted bipolar thermoelectricity in an asymmetric superconducting junction. The two superconductors have different gaps and are subject to a temperature difference T1>T2.

Figure 2. Non-linear thermoelectricity (red) and cooling (blue) regions for a superconducting junction. Thermoelectricity and refrigeration are complementary effects: the second law of thermodynamics prevents a thermodynamical machine from operating as a heat engine and a cooler at the same time.