Moiré Superlattice

Recently TMD moiré superlattices have been shown to host hybrid excitonic states[1], localised quantum emitters[2] and tuneable correlated electronic states including Mott insulating and Wigner crystalline phases[3][4]. MoSe₂/WSe₂ heterostructures have been widely studied as a host of band-edge interlayer excitons. However, optical signatures of moiré flat bands in these structures have thus far proved elusive. We perform resonant absorption spectroscopy of intralayer excitons in a dual-gate tuneable angle-aligned MoSe₂/WSe₂ heterostructure at 4K. We see evidence for the formation of moiré minibands and, in the hole-doping regime, observe the WSe₂ attractive and repulsive polarons exhibit doping dependent extra-ordinary g-factors and magnetic saturation behaviour[5]. We measure the magnetic phase diagram by tuning the fractional filling and observe peaks in the landé g-factor at 1/3, 2/3 and 1 hole per moiré site which we interpret as the formation of correlated states. Finally the peak position and intensity of the MoSe₂ A-exciton are shown to be sensors of the filling factor of the WSe₂ valence band.

[1] Y. Shimazaki et al. Nature (2020)
[2] H. Baek et al. Sci. Adv. (2020)
[3] Y. Tang et al. Nature (2020)
[4] E. Regan et al. Nature (2020)
[5] D. Efimkin et al. Phys. Rev. B (2017)