Superconductivity-driven ferromagnetism and spin manipulation using vortices in the magnetic superconductor EuRbFe 4 As 4

Significance The interplay between superconductivity and magnetism creates numerous exotic physical phenomena, while the two phenomena rarely coexist in one material because they compete with each other. The recently discovered iron-based magnetic superconductor EuRbFe 4 As 4 shows high-critical-temperature superconductivity and helimagnetic order at the ground state. We revealed that ferromagnetic alignment of Eu 2+ moments is induced by superconducting vortices in EuRbFe 4 As 4 by combining neutron diffraction and magnetization experiments. The direction of the Eu 2+ moments is dominated by the distribution of pinned vortices based on the critical state model, highlighting a unique interplay between magnetism and superconductivity. The capability of manipulating the spin texture by controlling the direction of superconducting vortices paves the way to novel devices using magnetic superconductors.