Abstract

Stacking monolayer semiconductors results in moiré patterns that host many correlated and topological electronic phenomena, but measurements of the basic electronic structure underpinning these phenomena are scarce. Here, we investigate the properties of the conduction band in moiré heterobilayers using submicron angle-resolved photoemission spectroscopy with electrostatic gating, focusing on the example of WS₂/WSe2. We find that at all twist angles the conduction band edge is the K-point valley of the WS2, with a band gap of 1.58 ± 0.03 eV. By resolving the conduction band dispersion, we observe an unexpectedly small effective mass of 0.15 ± 0.02 me. In addition, we observe replicas of the conduction band displaced by reciprocal lattice vectors of the moiré superlattice. We present arguments and evidence that the replicas are due to modification of the conduction band states by the moiré potential rather than to final-state diffraction. Interestingly, the replicas display an intensity pattern with reduced, 3-fold symmetry, which we show implicates the pseudo vector potential associated with in-plane strain in moiré band formation.

Abstract

Stacking monolayer semiconductors results in moiré patterns that host many correlated and topological electronic phenomena, but measurements of the basic electronic structure underpinning these phenomena are scarce. Here, we investigate the properties of the conduction band in moiré heterobilayers using submicron angle-resolved photoemission spectroscopy with electrostatic gating, focusing on the example of WS₂/WSe2. We find that at all twist angles the conduction band edge is the K-point valley of the WS2, with a band gap of 1.58 ± 0.03 eV. By resolving the conduction band dispersion, we observe an unexpectedly small effective mass of 0.15 ± 0.02 me. In addition, we observe replicas of the conduction band displaced by reciprocal lattice vectors of the moiré superlattice. We present arguments and evidence that the replicas are due to modification of the conduction band states by the moiré potential rather than to final-state diffraction. Interestingly, the replicas display an intensity pattern with reduced, 3-fold symmetry, which we show implicates the pseudo vector potential associated with in-plane strain in moiré band formation.

Abstract

Stacking monolayer semiconductors results in moiré patterns that host many correlated and topological electronic phenomena, but measurements of the basic electronic structure underpinning these phenomena are scarce. Here, we investigate the properties of the conduction band in moiré heterobilayers using submicron angle-resolved photoemission spectroscopy with electrostatic gating, focusing on the example of WS₂/WSe2. We find that at all twist angles the conduction band edge is the K-point valley of the WS2, with a band gap of 1.58 ± 0.03 eV. By resolving the conduction band dispersion, we observe an unexpectedly small effective mass of 0.15 ± 0.02 me. In addition, we observe replicas of the conduction band displaced by reciprocal lattice vectors of the moiré superlattice. We present arguments and evidence that the replicas are due to modification of the conduction band states by the moiré potential rather than to final-state diffraction. Interestingly, the replicas display an intensity pattern with reduced, 3-fold symmetry, which we show implicates the pseudo vector potential associated with in-plane strain in moiré band formation.

Abstract

Stacking monolayer semiconductors results in moiré patterns that host many correlated and topological electronic phenomena, but measurements of the basic electronic structure underpinning these phenomena are scarce. Here, we investigate the properties of the conduction band in moiré heterobilayers using submicron angle-resolved photoemission spectroscopy with electrostatic gating, focusing on the example of WS₂/WSe2. We find that at all twist angles the conduction band edge is the K-point valley of the WS2, with a band gap of 1.58 ± 0.03 eV. By resolving the conduction band dispersion, we observe an unexpectedly small effective mass of 0.15 ± 0.02 me. In addition, we observe replicas of the conduction band displaced by reciprocal lattice vectors of the moiré superlattice. We present arguments and evidence that the replicas are due to modification of the conduction band states by the moiré potential rather than to final-state diffraction. Interestingly, the replicas display an intensity pattern with reduced, 3-fold symmetry, which we show implicates the pseudo vector potential associated with in-plane strain in moiré band formation.