Physics Colloquia with Allan MacDonald

Abstract: 

Recent progress in two-dimensional materials has made the fabrication of artificial two-dimensional crystals – moiré materials [1-3] - with lattice constants on the 10 nm scale routine.  The significance of the large lattice constants is that it allows the number of electrons per effective atom in these crystals to be varied by around ten using electrical gates – effectively moving continuously across that many rows of the artifical material’s periodic table.  Since I last spoke on this topic at our physics department colloquium (between five and ten years ago?), moiré materials have been established as a rich platform for fundamental many-electron physics studies – realizing almost all phenomena known from decades of study of atomic-scale crystals and many-new phenomena related to strong correlations in materials with topologically non-trivial energy bands.  My update will focus on recent work related to the fractional quantum anomalous Hall effect in MoTe₂ homobilayer moiré materials [3].

[1] R. Bistritzer, and A.H. MacDonald, Proceedings of the National Academy of Sciences 26, 12233 ( 2011).

[2] F. Wu, T. Lovorn, E. Tutuc, and A.H. MacDonald, Phys. Rev. Lett. 121, 026402 (2018).

[3] F. Wu, T. Lovorn, E. Tutuc, I. Martin, and A.H. MacDonald, Phys. Rev. Lett. 122, 086402 (2019).