Observation of superconducting gap spectra of long-range proximity effect in Au /SrTiO3/SrRuO3/Sr2RuO4 tunnel junctions
Abstract
We observe an unconventional superconducting minigap induced into a ferromagnet SrRuO3 from a spin-triplet superconductor Sr2RuO4 using an 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 the surface of a 15-nm-thick SrRuO3 layer confirms the spin-triplet nature of induced superconductivity. The shape and temperature dependence of the gap features in the differential conductance suggest 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 an induced minigap in a ferromagnet, and it significantly advanced our understanding of the spin-triplet proximity effect between unconventional superconductors and ferromagnets.
- Publication:
-
Physical Review B
- Pub Date:
- July 2019
- DOI:
- 10.1103/PhysRevB.100.024516
- arXiv:
- arXiv:1903.02093
- Bibcode:
- 2019PhRvB.100b4516A
- Keywords:
-
- Condensed Matter - Superconductivity
- E-Print:
- Phys. Rev. B 100, 024516 (2019)