Charge carriers in two-dimensional transition metal dichalcogenides (TMDs), such as WSe₂, have their spin and valley-pseudospin locked into an optically addressable index that is proposed as a basis for future information processing^1,2. The manipulation of this spin–valley index, which carries a magnetic moment³, requires tuning its energy. This is typically achieved through an external magnetic field (B), which is practically cumbersome. However, the valley-contrasting optical Stark effect achieves valley control without B, but requires large incident powers^4,5. Thus, other efficient routes to control the spin–valley index are desirable. Here we show that many-body interactions among interlayer excitons (IXs) in a WSe₂/MoSe₂ heterobilayer (HBL) induce a steady-state valley Zeeman splitting that corresponds to B ≈ 6 T. This anomalous splitting, present at incident powers as low as microwatts, increases with power and is able to enhance, suppress or even flip the sign of a B-induced splitting. Moreover, the g-factor of valley Zeeman splitting can be tuned by ~30% with incident power. In addition to valleytronics, our results could prove helpful to achieve optical non-reciprocity using two-dimensional materials.

二维过渡金属二金属卤化物（TMD）（例如WSe ₂）中的电荷载体将其自旋和谷-假自旋锁定到光学可寻址索引中，该索引可作为未来信息处理^1,2的基础。带有磁矩^3的自旋谷指数的操纵需要调节其能量。这通常是通过外部磁场（B）来实现的，该磁场实际上很麻烦。但是，与山谷形成鲜明对比的光学斯塔克效应无需B即可实现山谷控制，但需要较大的入射功率^4,5。因此，需要其他有效的途径来控制自旋谷指数。这里，我们显示中间层的激子WSE（IXS）中，许多体相互作用₂ /摩西₂ heterobilayer（HBL）诱导稳态谷塞曼分裂对应于乙 ≈6 T.这异常分裂，存在于入射功率为低至微瓦，随功率而增加，并且能够增强，抑制甚至翻转B诱导分裂的迹象。此外，谷底塞曼分裂的g因子可以用入射功率调整〜30％。除了Valleytronics，我们的研究结果还可能有助于使用二维材料实现光学不可逆性。