Tunable layer-locked valley Hall effect in ferroelectric-magnetic-valley coupled breathing Kagome bilayer W3Br8

Based on an effective k·p model, we form breathing Kagome bilayers with two different interlayer antiferroelectric (AFE) couplings, i.e., tail to tail and head to head, to study their magnetic and valley properties. Spin–orbit coupling and magnetic exchange interaction induce valley-layer locking when the bilayer is ferromagnetic, however, spin-layer locking appears for the case of antiferromagnetic states. The inequivalent interlayer antiferroelectric couplings correspond to different magnetic ground states, and the antiferroelectric states can be switched through the breathing process, so the ferroelectric, magnetic, and valley properties can be simultaneously modulated. Through first-principles calculations, we also predict a favorable breathing Kagome bilayer W3Br8, where the above coupling mechanism and tunable layer-locked valley Hall effects can be achieved. Our findings provide an applicable paradigm for achieving ferroelectric–magnetic–valley coupling in a single device, driving the development of next-generation electronic devices.