Light-induced anomalous Hall effect in graphene*

In this talk I will discuss our recent observation of an anomalous Hall effect in monolayer graphene driven by a femtosecond pulse of circularly polarized light [1]. This was achieved using an ultrafast device architecture based on photoconductive switches. The dependence of the Hall effect on a gate potential used to tune the Fermi level reveals multiple features that reflect a Floquet-engineered topological band structure [2], similar to the band structure originally proposed by Haldane [3]. This includes an approximately 60 meV wide conductance plateau centered at the charge neutrality point, where a gap of equal magnitude is predicted to open. We find that when the Fermi level lies within this plateau, the non-equilibrium anomalous Hall conductance saturates around 1.8±0.4 e^2/h.

References
[1] J.W. McIver et al. Nature Physics (forthcoming); arXiv:1811.03522 (2019)
[2] T. Oka & H. Aoki. Phys. Rev. B 79, 081406 (2009)
[3] F.D.M. Haldane, Phys. Rev. Lett. 61, 2015-2018 (1988)