PHYS Seminar: “Nonlinear quantum transport in 2D materials”, Habib Rostami, 3:30PM December 6 (EN)

Assist. Prof. Dr. Habib Rostami
University of Bath

“Nonlinear quantum transport in 2D materials”

Nonlinear transport phenomena, such as charge and spin photogalvanic effects, are currently receiving significant attention due to their relevance in both fundamental research and practical applications. Nonlinear response can be understood through higher order correlation functions, which can relate to topological and many-body properties that cannot be captured by the linear response theory. In the first part of the talk, I will introduce a many-body formalism to investigate coherent THz third-harmonic generation of Dirac fermions in graphene [1, 2]. I will then emphasize the crucial role of vertex corrections in the nonlinear DC transport regime of graphene, where even an elastic impurity scattering can result in self-generated two-photon couplings to electrons. Our theoretical predictions indicate that self-generated two-photon vertex plays a dominant role in the nonlinear dc conductivity of Dirac electrons in graphene. In second part of the presentation, I will discuss the nonlinear Hall effects in charge and spin channels in WTe2 [3, 4]. I will focus on an inter-band resonance and enhancement of Berry curvature dipole describing the second-order Hall effect and an in-gap nonlinear spin Hall current which is a third-order rectification response. Finally, if time allows, I will briefly discuss novel nonlinear transport effects in two-dimensional topological Fermi liquid systems.

Habib Rostami completed his PhD in Physics at IPM in Tehran, Iran, in 2015 and worked as a researcher in Italy (at Scuola Normale Superiore di Pisa and IIT in Genoa) and Sweden (at Nordita/Stockholm University) from 2015 to 2022. A year ago, he joined the Department of Physics at the University of Bath in the UK as an Assistant Professor. Currently, his research activities and interests covers various areas of theoretical condensed matter physics, including nonlinear optical spectroscopy, nonlinear quantum transport, strain physics/engineering, and nonlinear phononics in two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs), along with their heterostructures.

Date : December 6, 2023 Wednesday
Time : 15:30
Place : SA-240

All interested are cordially invited.