Electrically controlled large valley polarization and anomalous valley Hall effect in antiferromagnet bilayer Fe 2 CF 2

Abstract Two-dimensional antiferromagnetic (AFM) valley materials have emerged as promising platforms for simultaneously harnessing valley polarization and magnetic order. Yet, realizing a robust anomalous valley Hall effect (AVHE) remains challenging because of spin degeneracy and the inherent difficulty of controlling valley polarization. In this work, we perform a systematic first-principles study of the electronic structure and magneto-valley coupling in bilayer AFM MXene Fe 2 CF 2 . We show that AB-stacked bilayer Fe 2 CF 2 adopts an AFM ground state, and crucially hosts an intrinsic out-of-plane ferroelectric polarization and a large valley splitting of 97 meV, the highest value reported to date for an AFM bilayer. Even more striking, a lateral interlayer shift reverses the ferroelectric polarization and, at the same time, swaps the dominant valley contributions from the top to the bottom layer. This effect enables electrically switchable control of the AVHE based on bistable stacking states without the need for an external magnetic field. Our findings establish Fe 2 CF 2 as a prototype for AFM-based valleytronic devices in which the valley Hall response can be written and read out electrically, opening a new route to low-power spin–valley functionalities.