Jack Engdahl

I am a full-time PhD candidate at UNSW Sydney in the School of Physics studying theoretical condensed matter physics. I completed my undergraduate degrees at UNSW in Mechanical Engineering and Physics. I mainly work on analytical solutions and perform exact numerical calculations when required. My research interests are broadly many body physics in 2D materials and fluid mechanics. Specifically I have completed projects in electron hydrodynamics, exciton physics and self-energy renormalisation due to many body screening.

Project: Effects of Electron-Electron Interactions in Two Dimensional Systems and Their Response to External Electric and Magnetic Fields

Supervised by: Prof. Oleg P. Sushkov

Project description: 

Electron-electron interactions in 2D materials give rise to several interesting phenomena which may be of great importance in the development of novel low energy electronic devices.

Firstly, electron-electron scattering in ultra-clean semiconductors leads to the regime of viscous electron hydrodynamics where the electrons flow similarly to a classical fluid. This flow may be controlled both geometrically and magnetically, leading to a new way to study electron-electron interactions, unique manifestations of fluid dynamics and also an entirely new regime of charge transport in which to design electronic devices. I study new ways to control the electron fluid.

The Coulomb interaction between an electron in the conduction band and a hole (absence of electron) in the valence band may lead to a bound state known as an exciton. Excitons effect the optical properties of a material and are also of interest regarding their ability to form superfluids or light matter coupling as an exciton-polariton. In my work I study the properties of excitons in 2D materials and their interaction with external electric and magnetic fields.

Electron-electron interactions also govern the self-energy of quasiparticles. Screening of the Coulomb interaction by charge carriers leads to a change in the band gap of a semiconductor, greatly influencing its properties and its applicability in certain electronic devices. In my work I study the band gap renormalisation of 2D materials due to many body screening.