Controlling the perpendicular magnetic anisotropy (PMA) in thin films has received considerable attention in recent years due to its technological importance. PMA based devices usually involve heavy-metal (oxide)/ferromagnetic-metal bilayers, where, thanks to interfacial spin-orbit coupling (SOC), the in-plane (IP) stability of the magnetisation is broken. Here we show that in V/MgO/Fe(001) epitaxial junctions with competing in-plane and out-of-plane (OOP) magnetic anisotropies, the SOC mediated interaction between a ferromagnet (FM) and a superconductor (SC) enhances the effective PMA below the superconducting transition. This produces a partial magnetisation reorientation without any applied field for all but the largest junctions, where the IP anisotropy is more robust; for the smallest junctions there is a reduction of the field required to induce a complete OOP transition (\(H_\text {OOP}\)) due to the stronger competition between the IP and OOP anisotropies. Our results suggest that the degree of effective PMA could be controlled by the junction lateral size in the presence of superconductivity and an applied electric field. We also discuss how the \(H_\text {OOP}\) field could be affected by the interaction between magnetic stray fields and superconducting vortices. Our experimental findings, supported by numerical modelling of the ferromagnet-superconductor interaction, open pathways to active control of magnetic anisotropy in the emerging dissipation-free superconducting spin electronics.

由于其技术重要性，控制薄膜中的垂直磁各向异性（PMA）近年来受到了相当大的关注。基于 PMA 的器件通常涉及重金属（氧化物）/铁磁金属双层，其中，由于界面自旋轨道耦合 (SOC)，磁化的面内 (IP) 稳定性被破坏。在这里，我们展示了在具有竞争性面内和面外 (OOP) 磁各向异性的 V/MgO/Fe(001) 外延结中，铁磁体 (FM) 和超导体 (SC) 之间的 SOC 介导的相互作用增强了超导转变以下的有效 PMA。这产生了部分磁化重新定向，除了最大的结之外的所有结点都没有施加任何磁场，其中 IP 各向异性更加稳健；\(H_\text {OOP}\) ) 由于 IP 和 OOP 各向异性之间的竞争更加激烈。我们的结果表明，在存在超导性和外加电场的情况下，有效 PMA 的程度可以通过结横向尺寸来控制。我们还讨论了\(H_\text {OOP}\)场如何受到杂散磁场和超导涡流之间相互作用的影响。在铁磁体-超导体相互作用的数值模型的支持下，我们的实验结果为新兴的无耗散超导自旋电子学中磁各向异性的主动控制开辟了道路。