Department of Physics, University of Seoul, Seoul 02504, Korea.
Natural Science Research Institute, University of Seoul, Seoul 02504, Korea.
Phys Rev Lett. 2018 Oct 19;121(16):167001. doi: 10.1103/PhysRevLett.121.167001.
It has been recognized that the condensation of spin-triplet Cooper pairs requires not only broken gauge symmetry but also spin ordering as well. One consequence of this is the possibility of a Cooper-pair spin current analogous to the magnon spin current in magnetic insulators, the analogy also extending to the existence of the Gilbert damping of the collective spin-triplet dynamics. The recently fabricated heterostructure of the thin film of the itinerant ferromagnet SrRuO_{3} on bulk Sr_{2}RuO_{4}, the best-known candidate material for a spin-triplet superconductor, offers a promising platform for generating such spin current. We show how such heterostructure allows us to not only realize the long-range spin valve but also electrically drive the collective spin mode of the spin-triplet order parameter. Our proposal represents both a novel experimental realization of superfluid spin transport and a transport signature of the spin-triplet superconductivity therein.
人们已经认识到，自旋三重态库珀对的凝聚不仅需要破缺规范对称性，还需要自旋有序。这一结果的一个后果是可能存在类似于磁性绝缘体中磁振子自旋电流的库珀对自旋电流，这种类比也扩展到了集体自旋三重态动力学的 Gilbert 阻尼的存在。最近制备的 SrRuO_{3} 薄膜在大块 Sr_{2}RuO_{4}上的巡游铁磁体的异质结构，是已知的自旋三重态超导体的最佳候选材料，为产生这种自旋电流提供了一个很有前途的平台。我们展示了这种异质结构如何不仅可以实现长程自旋阀，还可以电驱动自旋三重态序参量的集体自旋模式。我们的建议既代表了超流自旋输运的一种新颖的实验实现，也是其中自旋三重态超导性的输运特征。
