Spincaloritronics with superconductor-ferromagnet heterostructures

• Applicant: Professor Dr. Wolfgang Belzig
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2014 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257730597

In the present project we would like to elucidate the potential of superconducting heterostructure for spincaloritronic effects. Based on our recent prediction of a giant thermoelectric effect due to electron-hole symmetry breaking by a ferromagnetic element in a superconducting heterostructure we now propose to investigate the connection of thermoelectricity to spin-dependent transport phenomena in those systems. We will treat both dissipative spin currents carried by quasiparticles as well as spin supercurrents created by unconventional triplet pairing and their interaction with and manipulation by thermal gradients and bias voltages. In a first step we will investigate how strong all the different effects are coupled at all in simple multi-terminal structures. Based on the outcome we will propose active structures, which will allow to switch (spin-)supercurrents by making use of a temperature bias and to manipulate the coupling of spin and thermal currents by a magnetic flux. The parameters of spin-active interfaces will play a central role in all our studies and we hope to contribute to a coherentdescription of spin-caloritronic effects by motivating experimental studies using superconductors. Preliminary estimates show that the thermoelectric figure of merit ZT~1 at low temperatures can be expected.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1538: Spin Caloric Transport (SpinCaT)