Effect of interlayer Dzyaloshinskii-Moriya interaction on spin structure in synthetic antiferromagnetic multilayers

Chiral magnetism defines the spin structure sense of rotation in magnetic films and stabilized by the interfacial Dzyaloshiniskii-Moriya interaction (DMI), which can be used to generate the chiral nature of magnetic textures like spin spirals and skyrmions. Here, the direct evidence of the interlayer DMI was observed at room temperature, by designing the synthetic system with a ferromagnet/insulating spacer/ferromagnet structure whose magnetic chirality can be effectively manipulated between ferromagnetic coupling and antiferromagnetic coupling by changing spacer thickness. The interlayer DMI breaks the symmetry of the magnetic reversal process, leading to chiral exchange-biased Hall loops, where the noncollinear magnetic states were systematically characterized and quantified by using polarized neutron reflectometry (PNR). PNR results indicate that the maximum angle of the canted magnetic moments for ferromagnetic coupling can reach as high as 11.5 degrees, which is stronger than that for antiferromagnetic coupling, suggesting the higher energy excitation of magnetic chirality. This canted spin structure is verified by first-principles calculation. Our findings should be greatly useful for the interfacial design of spintronic devices to control and tailor the magnetic chirality for the formation of the spin texture in high-density memory.