WEEKLY COLLOQUIUM
Thursday, February 6, 2025
3:05 - 4:20 PM
Location: Biological Sciences, Room 334
Cooperative Order from Flat Electron Bands in Twisted Bi-Layer Graphene
Dr. Jose Rodriguez
Professor
Department of Physics and Astronomy, California State University, Los Angeles
Bi-layer graphene that is twisted at the magic angle of 1.1 degrees shows flat electron bands that give rise to a plethora of ordered states. These include orbital magnetism and superconductivity. We shall study twisted bi-layer graphene at commensurate twist angles in the case of the simplest moire patterns that have no subcells. Electronic properties are described by an electron hopping model between nearest-neighbor carbon atoms on the twisted lattice of bi-layer graphene. Flat electron bands at a magic twist angle are recovered from the simplified model. Using the electron band structure derived from the electron hopping model, we find evidence for nesting of the Fermi surfaces by wavenumbers that describe 3-sublattice (Kekule) charge-density wave (CDW) order. We study the instability of the Fermi surfaces to such Kekule CDW order by adding on-site repulsive interactions within mean field theory.
Spring 2025 Department of Physics and Astronomy Colloquium Schedule
(This schedule will be updated throughout the semester.)
- Thursday, February 6: Dr. Jose Rodriguez, CSULA, "Cooperative Order from Flat Electron Bands in Twisted Bi-Layer Graphene"
- Thursday, February 13:
- Thursday, February 20:
- Thursday, February 27:
- Thursday, March 6:
- Thursday, March 13:
- Thursday, March 20:
- Thursday, March 27:
- Thursday, April 3: Spring Break, No Colloquium
- Thursday, April 10:
- Thursday, April 17:
- Thursday, April 24:
- Thursday, May 1:
Thursday, May 8:
End of Spring 2025 Semester