Direct penetration of spin-triplet superconductivity into a ferromagnet in Au/SrRuO3/Sr2RuO4 junctions

Efforts have been ongoing to establish superconducting spintronics utilizing ferromagnet/superconductor heterostructures. Previously reported devices are based on spin-singlet superconductors (SSCs), where the spin degree of freedom is lost. Spin-polarized supercurrent induction in ferromagnetic metals (FMs) is achieved even with SSCs, but only with the aid of interfacial complex magnetic structures, which severely affect information imprinted to the electron spin. Use of spin-triplet superconductors (TSCs) with spin-polarizable Cooper pairs potentially overcomes this difficulty and further leads to novel functionalities. Here, we report spin-triplet superconductivity induction into a FM SrRuO 3 from a leading TSC candidate Sr 2 RuO 4 , by fabricating microscopic devices using an epitaxial SrRuO 3 /Sr 2 RuO 4 hybrid. The differential conductance, exhibiting Andreev-reflection features with multiple energy scales up to around half tesla, indicates the penetration of superconductivity over a considerable distance of 15 nm across the SrRuO 3 layer without help of interfacial complex magnetism. This demonstrates potential utility of FM/TSC devices for superspintronics. The injection of spin-polarized supercurrent into a ferromagnet presents the possibility of zero-resistance spintronic devices. Here, the authors evidence the direct injection of spin polarized supercurrent into ferromagnetic SrRuO 3 from a candidate spin-triplet superconductor Sr 2 RuO 4 .