Realization of Dual Anomalous Valley Hall Effect in Antiferromagnetic HfN₂/MnPSe₃ Heterostructure

The absence of an anomalous valley Hall (AVH) effect in HfN 2 can be attributed to its protection by the time-inversion ( T ) symmetry, resulting in a valley degeneracy in K + / K – valleys. On the other hand, MnPSe 3 is protected by T and spatial inversion ( P ) symmetries, which prohibits spin splitting and consequently hinders the achievement of the AVH. Here, by combining model analysis and first-principles calculation, we construct a HfN 2 /MnPSe 3 van der Waals (vdW) heterostructure (HTS). In HfN 2 /MnPSe 3 HTS, MnPSe 3 generates a magnetic exchange field that breaks the T symmetry of HfN 2, resulting in the generation of an intrinsic spin valley Hall current. The introduction of the HfN 2 layer disrupts the PT symmetry of MnPSe 3, leading to valley spin splitting in K + / K – valleys. Without PT symmetry protection, the AVH effect is observed in the MnPSe 3 layer of HfN 2 /MnPSe 3 HTS. The valley splitting of the HfN 2 layer and MnPSe 3 layer in HfN 2 /MnPSe 3 HTS gives rise to two distinct valleys in K + / K – points at the valence band maximum, respectively. Additionally, valley polarization in HfN 2 /MnPSe 3 HTS can be flipped simultaneously by reversing the magnetization of the Mn atom. Moreover, HfN 2 /MnPSe 3 /Sc 2 CO 2 ferroelectric HTS has been constructed to achieve precise control of valley-to-nonvalley-electron conversion and semiconductor-to-metal conversion. Our work offers not only an alternative and controllable approach for realizing the spontaneous AVH effect in antiferromagnetic HTS, but also a platform for designing energy-efficient valleytronic devices.