MnAl*

Weyl semimetals have been extensively studied due to their exotic properties such as topological surface states and anomalous transport phenomena. Their band structure topology is usually predetermined by material parameters and can hardly be manipulated once the material is formed. By calculations and experiments, we reveal a tunable, giant anomalous Hall effect in the ferromagnet Co₂MnAl. The transition between Weyl points and nodal rings occurs when rotating the magnetization axis. We propose a material recipe to generate the giant anomalous Hall effect by gaping nodal rings without requiring the existence of Weyl points. In addition, experiments show the strong anomalous Hall effect even at room temperature with a large Hall angle 21%. Our work reveals an ideal intrinsically magnetic platform to explore the interplay between magnetic dynamics and topological physics for the development of a new generation of spintronic devices.