Spinon Pairing Induced by Chiral In-Plane Exchange and the Stabilization of Odd-Spin Chern Number Spin Liquid in Twisted MoTe2

The unusual structure and symmetry of low-energy states in twisted transition metal dichalcogenides leads to large in-plane spin-exchange interactions between spin-valley locked holes. We demonstrate that this exchange interaction can stabilize a gapped spin-liquid phase with a quantized spin-Chern number of 3 when the twist angle is sufficiently small and the system lies in a Mott insulating phase. The gapped spin liquid may be understood as arising from spinon pairing in the DIII Altland-Zirnbauer symmetry class. Applying an out-of-plane electric field or increasing the twist angle is shown to drive a transition, respectively, to an anomalous Hall insulator or an in-plane antiferromagnet. Recent experiments indicate that a spin-Chern number 3 phase occurs in twisted MoTe₂ at small twist angles with a transition to a quantum anomalous Hall phase as the twist angle is increased above a critical value of about 2. 5° in the absence of an applied electric field.