We observe an unconventional superconducting minigap induced into a ferromagnet SrRuO3 from a spin-triplet superconductor Sr2RuO4 using a Au/SrTiO3/SrRuO3/Sr2RuO4 tunnel junction. Voltage bias differential conductance of the tunnel junctions exhibits V-shaped gap features around zero bias, corresponding to a decrease in the density-of-states with an opening of a superconducting minigap in SrRuO3. Observation of a minigap at a surface of a 15 nm thick SrRuO3 layers confirms the spin-triplet nature of induced superconductivity. The shape and temperature dependence of the gap features in the differential conductance indicate that the even-frequency p-wave correlations dominate, over odd-frequency s-wave correlations. Theoretical calculations support this p-wave scenario. Our work provides the density-of-states proof for p-wave Cooper pair penetration in a ferromagnet and significantly put forward our understanding of the p-wave spin-triplet proximity effect between spin-triplet superconductors and ferromagnets.

We study the tunneling conductance of a ballistic normal metal / ferromagnet / spin-triplet superconductor junction using the extended Blonder-Tinkham-Klapwijk formalism as a model for a c-axis oriented Au / SrRuO3 / Sr2RuO4 junction. We compare chiral p-wave (CPW) and helical p-wave (HPW) pair potentials, combined with ferromagnet magnetization directions parallel and perpendicular to the interface. For fixed θM , where θM is a direction of magnetization in the ferromagnet measured from the c-axis, the tunneling conductance of CPW and HPW clearly show different voltage dependencies. It is found that the cases where the d-vector is perpendicular to the magnetization direction (CPW with θM = π/2 and HPW with θM = 0) are identical. The obtained results serve as a guide to determine the pairing symmetry of the spin-triplet superconductor Sr2RuO4.arXiv:1804.07678v2 [cond-mat.supr-con]

Spin-polarized supercurrents can be generated with magnetic inhomogeneity at a ferromagnet/spin-singlet-superconductor interface. In such systems, complex magnetic inhomogeneity makes it difficult to functionalise the spin-polarized supercurrents. However, spin-polarized supercurrents in ferromagnet/spin-triplet-superconductor junctions can be controlled by the angle between magnetization and spin of Copper pairs (d-vector), that can effectively be utilized in developing of a field of research known as superconducting spintronics. Recently, we found induction of spin-triplet correlation into a ferromagnet SrRuO3 epitaxially deposited on a spin-triplet superconductor Sr2RuO4, without any electronic spin-flip scattering. Here, we present systematic magnetic field dependence of the proximity effect in Au/SrRuO3/Sr2RuO4 junctions. It is found that induced triplet correlations exhibit strongly anisotropic field response. Such behaviour is attributed to the rotation of the d-vector of Sr2RuO4. This anisotropic behaviour is in contrast with the vortex dynamic. Our results will stimulate study of interaction between ferromagnetism and unconventional superconductivity.

SrRuO3 is known to exhibit strong magnetocrystalline effect, which enables us to control its magnetic properties using lattice engineering. The magnetocrystalline effect of SrRuO3 is systematically investigated under both compressive and tensile strain by depositing SrRuO3 thin films on various oxide substrates with different in‐plane lattice mismatch. All SrRuO3 films have high crystallinity with flat interface and surface. It is found that out‐of‐plane lattice constant is decreased with increasing strain. Moreover, unit cell volume decreases with strain due to structural distortion attributable to RuO6 octahedral distortion as theoretically expected. However, magnetization does not match to any of the theoretical models only considering structural changes; at current stage, internal interactions rather than structural changes seem critical in determining the magnetization of the SrRuO3 films. This study can play a crucial role in understanding internal correlations of magnetic properties in ruthenate films and can trigger research on magnetic functionality.