Spincaloritronics with superconductor-ferromagnet heterostructures

在本项目中，我们想要阐明超导异质结构在自旋电子效应中的潜力。基于我们最近对超导异质结构中铁磁元素因电子-空穴对称破缺而产生的巨大热电效应的预测，我们现在提议研究这些系统中热电与自旋相关输运现象的联系。我们将讨论准粒子携带的耗散自旋电流和非常规三重态配对产生的自旋超电流，以及它们与热梯度和偏置电压的相互作用和操纵。在第一步中，我们将研究在简单的多端结构中，所有不同的效应是如何耦合的。基于结果，我们将提出主动结构，它将允许通过利用温度偏置来切换（自旋）超电流，并通过磁通量来操纵自旋和热流的耦合。自旋活性界面的参数将在我们所有的研究中发挥核心作用，我们希望通过激发超导体的实验研究，为自旋热电子效应的相干描述做出贡献。初步估计表明，在低温下可以得到优良的热电图ZT~1。

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.