Superconductivity-induced change in magnetic anisotropy in epitaxial ferromagnet-superconductor hybrids with spin-orbit interaction

Unlike the common expectation that superconducting spintronics and long-range triplet (LRT) proximity effects require complex ferromagnetic multilayers, noncollinear magnetization or half-metals, we propose a platform compatible with commercial spintronics. We have experimentally demonstrated that interfacial spin-orbit coupling (SOC) and symmetry-filtering in all-epitaxial V/MgO/Fe junctions, cooled below the critical temperature of vanadium, provide a thousand-fold increase in tunneling anisotropic magnetoresistance, supporting the LRT formation [1]. Here we report the converse effect: transformation of the magnetocrystalline anisotropy of a Fe(001) layer driven by the superconductivity of vanadium through a spin-orbit coupled MgO interface [2]. We attribute this to an additional contribution to the free energy of the ferromagnet arising from the controlled generation of triplet Cooper pairs, which depends on the relative angle between the exchange field of the ferromagnet and the spin-orbit field. This observation offers the ability to tune magnetic anisotropies using superconductivity - a key step in designing future cryogenic magnetic memories. [1] I. Martínez et al; Phys. Rev. Appl. 13, 014030 (2020); [2] C. González-Ruano et al; Phys. Rev. B, 020405(R) (2020).