Twistronics of 2D materials: from modelling to real systems

Venue: National Graphene Institute of the University of Manchester (in-person, talks can be attended remotely via zoom)

Stacked van der Waals multilayers exhibit a moiré pattern if the constituent monolayers have different lattice constants or are twisted relative to each other. These moiré patterns give rise to fascinating new properties, including correlated insulator states, unconventional superconductivity, flat electron and phonon bands, moiré excitons as well as topological states. Example systems include twisted bilayer graphene or twisted bilayers of transition metal dichalcogenides. Despite many advances, these moiré materials remain challenging to study from a theoretical point of view because they combine two unique challenges: (i) the unit cells of moiré materials are extremely large often containing thousands of atoms and (ii) electrons in these materials are strongly correlated. As a consequence, there are no “off-the-shelf” methods and computer codes available for the modelling of these materials.

Our workshop aims to bring together researchers from different modelling communities (including those using atomistic ab initio approaches, continuum approaches, emergent moiré lattice models, topological methods, strong correlation as well as excited state and non-equilibrium techniques) as well as experimentalists to identify synergies and possible ways forward.

To make the workshop accessible for students, we will begin each topical session with a tutorial talk that introduces the relevant concepts.

The workshop will be run jointly by the UK’s National Graphene Institute (Manchester), the Thomas Young Centre for Theory and Simulation of Materials (London), and the Sir Henry Royce Institute and has received funding from the Psi-k Charity (http://psi-k.net/), CCP9 and the Institute of Physics.

Registration fee: attendance of the workshop is free

Wednesday, September 20 

09.30: Arrival, registration, coffee
10.00: Welcome (Vladimir Falko)

10.10: Session 1: Twisted graphene materials I (Chair: Nicholas Hine)
10.10: Tim Kaxiras (invited): Twisted bilayer graphene revisited: where is the “magic”?
10.40: Niels Walet (contributed): Electronic structure inside the domain walls of twisted and strained graphene layers
11.00: Alessandro Principi (contributed): Interlayer electron-hole friction in tunable twisted bilayer graphene semimetal
11.20: Angelika Knothe (invited): Regular and chaotic electron dynamics in ballistic (twisted) bilayer graphene cavities
11.50: Darryl Foo (contributed): Extended magic phase in twisted graphene multilayers

12.10: Lunch & Poster session

13.30: Session 2: Twisted graphene materials II (Chair: Dahlia Klein)
13.30: Sid Parameswaran (invited): A Spiral Twist to the “Normal” State of Moiré Graphene
14.00: Sankalpa Ghosh (contributed): Moiré fractals in twisted graphene layers
14.20: Irina Grigorieva (invited): Magnetic-field induced phase transition in heterostructures based on unconventional superconductor PdBi₂
14.50: Mohammed Al Ezzi (contributed): Topological Flat Bands in Graphene Super-moiré Lattices

15.10: Coffee break

15.30: Session 3: Twisted graphene materials III (Chair: Kristian Thygesen)
15.30: Artem Mishchenko (invited): Moiré effects in thick graphitic films with surface layer aligned with hBN 
16.00: Mei-Yin Chou (contributed): Origin of Magic Angles in Twisted Bilayer Graphene: The Magic Ring
16.20: Maxim Trushin (contributed): Electron pairing across a band intersection may create a highly conductive state
16.40: Francesco Guinea (invited): Superconductivity in graphene stacks.

Thursday, September 21

09.20: Session 1: Twisted TMDs I (Chair: Neil Drummond)
09.20: Steven Louie (invited): Excitons and photophysics of 2D van der Waals structures
09.50: Sufei Shi (invited): Valley-polarized Exitonic Mott Insulator in WS2/WSe2 Moiré Superlattices

10.20: Coffee break

10.40: Session 2: Twisted TMDs II (Chair: Sid Parameswaran)
10.40: Brian Gerardot (invited): Optically probing correlated states in mult-orbital moiré systems
11.10: Andres Grandos del Aguila (contributed): Ultrafast exciton fluid flow in an atomically-thin MoS2 semiconductor
11.30: Guang-Yu Guo (contributed): Ab initio studies of nonlinear optical responses of 2D semiconductors
11.50: Samuel Magorrian (contributed): One-dimensional confinement in moiré superlattices of twisted 1T’-WTe2 bilayers
12.10: Sergey Slizovskiy (contributed): Kagome quantum oscillations in graphene superlattices

12.30: Lunch & Poster session

13.30: Session 3: Twisted TMDs III (Chair: Angelika Knothe)
13.30: Adina Luican-Mayer (invited): Scanning Tunneling Microscopy of twisted 2D semiconductors
14.00: Andor Kormanyos (contributed): Induced spin-orbit coupling in twisted graphene-TMDC heterobilayers
14.20: Kristian Thygesen (invited): Emergent properties of van der Waals bilayers revealed by computational stacking

14.50: Coffee break

15.10: Session 4: Twisted TMDs IV (Chair: Sarah Haigh)
15.10: Nicholas Hine (invited): Combining Large Scale DFT and Machine Learned Interatomic Potentials to Simulate Twisted Bilayers, Heterostructures and Alloys of 2D Materials
15.40: Pierre Pantaleon-Peralta (contributed): Designing Moiré Patterns by Strain
16.00: Aitor Garcia-Ruiz (contributed): FE polarization in mixed-stacking graphene tetra layers

Friday, September 22

09.20: Session 1: (Chair: Sufei Shi)
09.20: Sarah Haigh (invited): Understanding Twisted 2D material heterostructures Using Scanning Transmission Electron Microscopy
09.50: Neil Drummond (invited): Adhesion of Graphene to Hexagonal Boron Nitride

10.20: Coffee break

10.40: Session 2: (Chair: Brian Gerardot)
10.40: Dahlia Klein (invited): Atomic SET: a new technique for high-resolution potential imaging
11.10: Lorenzo Sponza (contributed): Electronic structure and optical response of twisted boron nitride bilayers
11.30: Sushant Kumar Behera (contributed): Engineering Moiré Potential Induced Electronic Structure in van der Waals heterostructure
11.50: Allan MacDonald (invited): Magic Angles and Fractional Chern Insulators in Twisted Homobilayer TMDs
12.20: Closing (Johannes Lischner)

Organizers:
Johannes Lischner (Imperial College London, j.lischner@imperial.ac.uk)
Vladimir Falko (University of Manchester, Vladimir.Falko@manchester.ac.uk)

https://www.royce.ac.uk/events/twistronics-of-2d-materials-from-modelling-to-real-systems/