Two-dimensional valleys and magnetism are rising areas with intriguing properties and practical uses in advanced information technology. By coupling valleys to collinear magnetism, valley degeneracy is lifted in a large number of magnetic valley materials to exploit the valley degree of freedom. Beyond collinear magnetism, new coupling modes between valley and magnetism are few but highly desirable. By tight-binding calculations of a breathing Kagome lattice, we demonstrate a tunable valley structure and valley-contrasting physical properties in noncollinear antiferromagnets. Distinct from collinear magnetism, noncollinear antiferromagnetic order enables valley splittings even without spin-orbit coupling. Both the canting and azimuthal angles of magnetic moments can be used as experimentally accessible knobs to tune valley splittings. Our first-principles calculations of the FeCO-silicene-FeCO heterostructure also exhibit tunable valley splittings in noncollinear antiferromagnetism, agreeing with our tight-binding results. Our work paves avenues for designing novel magnetic valley materials and energy-efficient valleytronic devices based on noncollinear magnetism.
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