Electronic structure of transition metal dichalcogenides under strain
Abstract
[EMBARGOED UNTIL 5/1/2024] The broken inversion symmetry in transition metal dichalcogenides(TMD) generates special orbital characters at the valley points in the Brillouin zone, which leads to various interesting phenomena such as the presence of large intrinsic orbital moment, orbital/spin Hall effect, etc. These quantities can be tuned by introducing strain to the system. Hence a strain-dependent Hamiltonian around these valleys is required to describe these effects. We present a systematic strain theory for the TMDs, by adopting a different approach than the earlier works, which leads to a simple and minimal tight binding valley orbital model (VOM). Our model not only describes the Hamiltonian at the K/K' valley points in the presence of strain but is also valid up to a linear order in q. This properly describes the shape change of the energy contours and the shift of the valley extrema points, with different components of the strain tensor. The total energy calculated from our Hamiltonian is consistent with the wellknown symmetry properties from the theory of elasticity. The strain Hamiltonian is validated by comparing it with the Density functional theory (DFT) results. Furthermore, we outline some of the physical quantities such as orbital Hall conductivity, spin Hall conductivity etc, which can be computed using our model Hamiltonian.
Degree
Ph. D.