Superconductivity-driven ferromagnetism and spin manipulation using vortices in the magnetic superconductor EuRbFe4As4

TL;DR

This paper reports the experimental discovery of vortex-induced ferromagnetism in EuRbFe4As4, revealing how superconducting vortices can control magnetic spin textures, opening pathways for spin manipulation devices.

Contribution

It demonstrates vortex-induced ferromagnetism and spin manipulation in a high-Tc magnetic superconductor, a novel phenomenon not previously observed in this material class.

Findings

Superconducting vortices induce ferromagnetic order in EuRbFe4As4.

The Eu2+ spin direction is governed by vortex distribution.

Spin textures can be manipulated by controlling vortex orientation.

Abstract

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.