  Magnetic superconductors are specific materials exhibiting two antagonistic
phenomena, superconductivity and magnetism, whose mutual interaction induces
various emergent phenomena, such as the reentrant superconducting transition
associated with the suppression of superconductivity around the magnetic
transition temperature (Tm), highlighting the impact of magnetism on
superconductivity. In this study, we report the experimental observation of the
ferromagnetic order induced by superconducting vortices in the
high-critical-temperature (high-Tc) magnetic superconductor EuRbFe4As4.
Although the ground state of the Eu2+ moments in EuRbFe4As4 is helimagnetism
below Tm, neutron diffraction and magnetization experiments show a
ferromagnetic hysteresis of the Eu2+ spin alignment. We demonstrate that the
direction of the Eu2+ moments is dominated by the distribution of pinned
vortices based on the critical state model. Moreover, we demonstrate the
manipulation of spin texture by controlling the direction of superconducting
vortices, which can help realize spin manipulation devices using magnetic
superconductors.
