Observation of Magnetic State Dependent Thermoelectricity in Superconducting Spin Valves

Superconductor-ferromagnet tunnel junctions demonstrate giant thermoelectric effects that are being exploited to engineer ultrasensitive terahertz radiation detectors. Here, we experimentally observe the recently predicted complete magnetic control over thermoelectric effects in a superconducting spin valve, including the dependence of its sign on the magnetic state of the spin valve. The description of the experimental results is improved by the introduction of an interfacial domain wall in the spin filter layer interfacing the superconductor. Surprisingly, the application of high in-plane magnetic fields induces a double sign inversion of the thermoelectric effect, which exhibits large values even at applied fields twice the superconducting critical field.

Automated summary

Superconductor-ferromagnet tunnel junctions have been used to engineer ultrasensitive terahertz radiation detectors by exploiting their giant thermoelectric effects. In this study, we experimentally observe complete magnetic control over the thermoelectric effects in a superconducting spin valve, including a dependence on the magnetism of the spin valve. The application of high in-plane magnetic fields leads to a double sign inversion of the thermoelectric effect, which remains large even at fields twice the superconducting critical field.