REU Project ID 4.5

Spontaneous symmetry breaking in graphene heterostructures

Prof. Mike Zaletel
Electron superlattice illustration

When atomically thin layers of graphene are stacked with a relative twist between them, the moire pattern formed by the beating between their crystal structures generates an superlattice for the motion of the electrons in the bilayer.

This superlattice changes the band structure of the electrons, and when the twist angle is at special “magic” angles it’s found that the kinetic energy of the electron vanishes. In this regime, the behavior of the electrons is governed predominantly by Coulomb repulsion, and it was recently discovered experimentally that this leads to highly correlated states of quantum matter including magnetism and superconductivity. We’re working to figure out why.

In this project we’ll use numerical techniques (DMRG) to help us understand what phases occur in magic-angle graphene, and why.