Study predicts a new quantum anomalous crystal in fractionally filled moiré superlattices
Moiré superlattices, structures that arise when two layers of two-dimensional (2D) materials are overlaid with a small twist angle, have been the focus of numerous physics studies. This is because they have recently been found to host novel fascinating unobserved physical phenomena and exotic phases of matter. (Phys.org)
Plot of the pair density correlation function, a quantity that characterizes crystallization, in the quantum anomalous Hall crystal. Arrows on the boundary denote the topological edge states. Credit: Sheng et al.
Researchers at California State University Northridge, Stockholm University and Massachusetts Institute of Technology (MIT) recently predicted the emergence of a new quantum anomalous state of matter in fractionally filled moiré superlattice bands. Their paper, published in Physical Review Letters, predicts the existence of this state of matter in the twisted semiconductor bilayer 𝑡MoTe2.
"This class of states may be quite common in moiré superlattices, with telltale experimental signatures including a quantized and surprisingly large zero-field Hall conductance," said Emil J. Bergholtz, co-author of the paper and professor at Fysikum.
"What makes this even more remarkable is that strong Coulomb interactions drive this state. Without these interactions, the system would behave like a simple metal. However, the topology of the strongly interacting system is nevertheless manifested in terms of effectively non-interacting fermions in the form of a Chern insulating state."
This project brings together several frontiers of basic science - from materials science and quantum optics to the theory of topological phases and modern mathematics - with a potential to provide a basis of future technology.
In this theoretical project, we intend to investigate what happens when we assemble exotic topological components. More specifically, we want to investigate four types of "sculptured topological heterostructures" as briefly described below.
Topological phases of matter are amongst the most interesting phases that are being studied, both theoretically as well as in experiments. In this project, we focus on the various types of phase transitions that topological phases can undergo.
WACQT is a national research programme, coordinated from Chalmers, that aims to take Swedish research and industry to the forefront of quantum technology.
The Bergholtz group explores the world of quantum and complex systems — what it is and what it could be — from the perspective of mathematics and theoretical physics.
