Towards control of the chirality sign at ultrathin metal films: Bi at 2Ni/Co

Abstract Proximity effects can be used to introduce spin–orbit interactions in magnetic metallic layers contact a heavy metal (HM). This well known phenomenon has been exploited induce chiral spin textures at Co ultrathin films, where the left- or right- handedness tuned by HM layer position, based on broken inversion symmetry of film and existence an additive interface effect. Here we show that structural chemical features introducing further reductions added this scenario ultimately enabling control over definition unique winding sense. We focus 2Ni/Co heterostructures Bi, scarcely explored large size, combine chemically inhomogeneous ferromagnetic stack along normal surface with in-plane asymmetries. Our results are contrasted 2Co combined Ir.