Superconducting stripes induced by ferromagnetic proximity in an oxide heterostructure

The intimate connection between magnetism and superconducting pairing plays a central role in determining the occurrence of unconventional superconducting states. In particular, magnetism can cause a modulation of superconducting pairing in real space in both copper-based and iron-based materials. Exploring this effect can shed light on the mechanism of unconventional superconductivity. Here we report on the discovery of a spatially varying superconducting state residing at the interface between KTaO 3 and ferromagnetic EuO. Electrical transport measurements reveal different values of the critical temperature and magnetic field at which the superconductivity breaks down when current is applied along the two orthogonal in-plane directions. This anisotropy occurs in low-carrier-density samples that are characterized by strong coupling between the Ta 5 d and Eu 4 f electrons, whereas in high-carrier-density samples, the coupling is weakened and the superconducting properties become isotropic. Our observations imply the emergence of superconducting stripes where phase coherence is established ahead of the rest of the interface, arising from a band-filling-dependent ferromagnetic proximity. Copper-based and iron-based compounds exhibit an interplay between magnetism and superconductivity. Now, this idea is extended to two-dimensional oxide heterostructures, where a spatially varying superconducting order is demonstrated at the EuO/KTaO 3 interface.