Fig. 3. Spin-dependent interlayer tunneling.

a Schematic of spin-dependent interlayer charge transfer over the MoSe₂/CrBr₃ interface. The type-II band alignment precludes a static electron doping in MoSe₂, and so we infer a resident hole population. In CrBr₃, the CB is strongly split into oppositely spin-polarized bands. Only the minority-spin bands are resonant with the MoSe₂ CB. Upon optical injection of electron-hole pairs, the electrons may tunnel from MoSe₂ to CrBr₃, with efficiency depending on their spin (green or purple indicate opposite spin). As CrBr₃ is transparent at our laser energy, absorption is negligible, and so we expect no appreciable dynamic hole transfer from CrBr₃ to MoSe₂. b Diagram of exciton dispersion in MoSe₂, with an energy splitting (the L-T splitting, see main text) proportional to in-plane wavevector k. The L-T splitting acts as an effective magnetic field inducing valley pseudospin relaxation in the presence of disorder scattering. Outside the light cone, efficient valley depolarization prevents spin-dependent tunneling from influencing the eventual DOCP. At low k, the spin-dependent tunneling is able to influence the DOCP observed in PL. At vanishing center of mass momentum, the exciton population either radiatively recombines (sub-ps) or else binds to a resident hole to form a long-lived trion valley state, which will be susceptible to spin-dependent tunneling. c Polarization resolved PL linewidths of the exciton (X) and trion (T). The trion linewidth shows opposing behavior in different polarizations, indicating that the lifetime is influenced by spin-dependent interlayer tunneling. The exciton has a constant linewidth, indicating insensitivity to CrBr₃ magnetization.