Non-magnetic spin splitting driven by spin-valley-layer coupling in multilayer WSe2

Transition metal dichalcogenides provide a platform for exploring spin-valley physics, offering a promising approach to electric-field-driven spin control for low-power spintronic and quantum devices. Here, we demonstrate electric-field-induced spin splitting in the Q and Q' valleys of multilayer n-type WSe2 using quantum-point-contact spectroscopy. Systematic modulations in four distinct conductance quantization steps, providing direct evidence of spin-valley-layer coupling-driven spin-resolved density of states, are achieved by tuning the out-of-plane gate voltage. Notably, the electric-field-induced spin splitting significantly dominate the magnetic-field-induced valley-Zeeman effect (i.e., ~7 meV for a displacement field change of ~0.08 V/nm vs. ~2 meV for a magnetic field of B = 9 T), demonstrating a powerful, non-magnetic manipulation of spin states. This ability to manipulate spin states by gate voltage is crucial for advancing next-generation low-power spintronic and quantum information technologies.