Interlayer exciton condensates in high Landau levels in bilayer WSe2

Exciton condensates (EC) have been realized in the quantum hall regime in GaAs double quantum wells and graphene double layers separated BN, appearing in the lowest Landau level (LL) with index N = 0. In these systems, the barrier thickness has to be carefully chosen in order to preserve strong interlayer Coulomb interaction but suppress tunneling at the same time. In bilayer WSe2, the spin-valley locking together with the valley misalignment in natural AB stacking, results in suppressed interlayer tunneling and allows independent control of the layer population. We observe signatures consistent with interlayer EC when the two layers have matched LL orbital wavefunctions. Unlike previous systems with intentional tunnel barrier, the natural bilayer has the interlayer spacing d as small as the lattice constant and the strong interlayer Coulomb interaction allows EC to be realized in N > 0 LLs. Compared to EC in the lowest LL, EC in high LLs turn out to be more robust in the low d/l_B limit (l_B is the magnetic length), and the charge gap demonstrates an opposite dependence against interlayer density imbalance.