Seminars Archive

Nonlinear optics in Dirac systems: the case of nonlinear Hall effect

Abstract
In this talk, I will discuss the nonlinear optical response of Dirac fermionic systems. Particularly, I will focus on the nonlinear Hall effect in response to a linearly polarized driving field. Interaction driven symmetry breaking in a metallic (doped) Dirac system can manifest in the spontaneous gap generation at the nodal point buried below the Fermi level. Across this transition linear conductivity remains finite making its direct observation is difficult in linear transport. In this talk, I will show how the nonlinear Hall effect can be used as a direct probe of this transition when inversion symmetry is broken. Specifically, for a two-dimensional Dirac material with a tilted low-energy dispersion, we first predict a transformation of the characteristic inter-band resonance peak into a non-Lorentzian form in the collisionless regime and a suppression of the nonlinear conductivity owing to the scattering between the strongly coupled incoherent fermionic and bosonic excitations.