Heterostrain-Induced\nZeeman-like Splitting in h‑BN-Encapsulated\nBilayer WSe<sub>2</sub>

Heterostrain is predicted to induce exceptionally rich\nphysics\nin atomically thin two-dimensional structures by modifying the symmetry\nand optical selection rules. In this work, we introduce heterostrain\ninto WSe<sub>2</sub> bilayers by combining h-BN encapsulation and\nhigh-temperature vacuum annealing. Nonvolatile heterostrain gives\nrise to a Zeeman-like splitting associated with the elliptically polarized\noptical emission of interlayer K–K excitons. Further manipulation\nof the interlayer exciton emission in an external magnetic field reveals\nthat the Zeeman-like splitting cannot be eliminated even in a magnetic\nfield of up to ±6 T. We propose a microscopic picture with respect\nto the layer and valley pseudospin to interpret the results. Our findings\nimply an intriguing way to encode binary information with the layer\npseudospin enabled by the heterostrain and open a venue for manipulating\nthe layer pseudospin with heterostrain engineering, optical pseudospin\ninjection, and an external magnetic field.