Abstract
The graphene family materials are two-dimensional staggered monolayers with a gapped energy band structure due to intrinsic spin-orbit coupling. The mass gaps in these materials can be manipulated on-demand via biasing with a static electric field, an off-resonance circularly polarized laser, or an exchange interaction field, allowing the monolayer to be driven through a multitude of topological phase transitions. We investigate the dynamics of spin-orbit coupled graphene family materials to unveil topological phase transition fingerprints embedded in the nonlinear regime and show how these signatures manifest in the nonlinear Kerr effect and in third-harmonic generation processes. We show that the resonant nonlinear spectral response of topological fermions can be traced to specific Dirac cones in these materials, enabling characterization of topological invariants in any phase by detecting the cross-polarized component of the electromagnetic field. By shedding light on the unique processes involved in harmonic generation via topological phenomena our findings open an encouraging path towards the development of novel nonlinear systems based on two-dimensional semiconductors of the graphene family.
Highlights
Graphene is the typical go-to material to investigate the optoelectronic response of two-dimensional (2D) systems[1,2] because of its extraordinary electron m obility[3], tunable linear electronic c onductivity[4], and potential for strong-light matter interactions at sub-wavelength s cales[5]
We explore the interplay between topological Dirac fermions in the graphene family materials (GFM) and optical fields beyond the linear regime
Our results show a rich structure of nonlinear optoelectronic responses across the phase diagram, and we demonstrate that the third-order optoelectronic conductivity contribution to the fundamental and third-harmonics encodes fingerprints of topological phase transitions
Summary
Graphene is the typical go-to material to investigate the optoelectronic response of two-dimensional (2D) systems[1,2] because of its extraordinary electron m obility[3], tunable linear electronic c onductivity[4], and potential for strong-light matter interactions at sub-wavelength s cales[5] It supports quantum Hall states in the presence of strong magnetic fields[6,7,8], the intrinsically weak spin-orbit coupling[9] severely limits graphene’s suitability to study topological phase transitions[10,11] in low-dimensional materials. The strong spin-orbit coupling in these systems results in a gapped bulk energy band-structure and protected one-way edge states characteristic of topological insulators They can be driven through a variety of phase transitions (Fig. 1a,b) by actively controlling the mass gap via external interactions[19], which could enable unprecedented all-in-one material multi-optoelectronic functionalities with potential applications to spintronics and valleytronics. Our work sets the cornerstones for investigating topological phase transitions beyond the linear response in the family of graphene-like elemental 2D materials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
