Condensed Matter Physics Seminar

Since its discovery more than three decades ago, the fractional quantum Hall effect has been studied almost exclusively in the two-dimensional electron systems formed in GaAs/AlGaAs heterojunctions. However, recent improvements in the quality of graphene have revealed a rich landscape of fractional quantum Hall states in this material, heralding the beginning of a new chapter in fractional quantum Hall physics. The N=0 Landau level of graphene is endowed with an approximate spin-valley SU(4) symmetry. In this talk, I will describe a variational approach to understand how this symmetry is broken, which allows to construct trial incompressible ground states, their charged quasi-particles and compute their associated gaps.