Title: Lattice disorder-driven charge transport and engineering structural phases in two dimensional layered materials

Speaker: Dr. Vidya Kochat, Rice University, USA

Abstract: Two dimensional layered materials, popularly known as 2D materials, have revolutionized the fields of physics and materials science in the last decade starting from the isolation of graphene, and is predicted to be the atomic nanosheet technology of the future. Graphene is a pioneering condensed matter system host to many relativistic phenomena. An understanding of the role played by lattice disorder in electronic transport is a prerequisite for the advances in technology envisioned for graphene. In this talk, I will show that topological defects such as grain boundaries significantly influence the charge transport by acting as strong sources of electrical noise especially at the room temperature, while at low temperatures leads to spontaneous time reversal symmetry breaking. I will also discuss the role of lattice defects in influencing the quantum transport and symmetry aspects of graphene. Transition metal dichalcogenides form another class of 2D materials that holds promise for future 2D nanoelectronics. These materials show correlated structural and electronic phases such that triggering structural transitions to other metastable phases also result in tunable metal-insulator/semiconductor electronic phase transitions. In this talk, I will discuss various strategies to tailor such structural phase transitions in 2D materials. Alloying/doping modulated structural instabilities during growth phase to realize composition tunable structural phases is one way of achieving this phase transition. Another potential pathway to induce structural phase transitions is through photo-induced non-radiative energy dissipation. I will discuss the strong lattice response to optical excitations which has important implications for light-induced structural-phase transition in transition metal dichalcogenides.