Abstract
The advent of topological phases of matter revealed a variety of observed boundary phenomena, such as chiral and helical modes found at the edges of two-dimensional (2D) topological insulators. Antichiral states in 2D semimetals, i.e., copropagating edge modes on opposite edges compensated by a counterpropagating bulk current, are also predicted, but, to date, no realization of such states in a solid-state system has been found. Here, we put forward a procedure to realize antichiral states in twisted van der Waals multilayers, by combining the electronic Dirac-cone spectra of each layer through the combination of the orbital moir\'e superstructure, an in-plane magnetic field, and inter-layer bias voltage. In particular, we demonstrate that a twisted van der Waals heterostructure consisting of graphene/two layers of hexagonal boron nitride [(hBN)$_2$]/graphene will show antichiral states at in-plane magnetic fields of 8 T, for a rotation angle of 0.2$^{\circ}$ between the graphene layers. Our findings engender a controllable procedure to engineer antichiral states in solid-state systems, as well as in quantum engineered metamaterials.
Highlights
Dirac materials have sparked vast interest in recent years, as their unique electronic properties offer a controllable setting with which to realize new states of matter [1,2], as well as engineer topological phenomena [3,4]
We have demonstrated that a twisted graphene/(hBN)2/graphene heterostructure at 0.2◦ rotation will show antichiral states for in-plane magnetic fields of 8 T
This fundamental idea consists of engineering a system hosting two Dirac points that can be shifted in energy by means of an interlayer bias
Summary
Dirac materials have sparked vast interest in recent years, as their unique electronic properties offer a controllable setting with which to realize new states of matter [1,2], as well as engineer topological phenomena [3,4]. A paradigmatic example of the versatility of the Dirac system consists of breaking time-reversal symmetry in the honeycomb lattice and opening up a valley-dependent mass [13] In this situation, a topologically nontrivial bulk gap opens at the Dirac points, and the above-mentioned flat edge band develops into the chiral subgap modes of a Chern insulator, where the latter are dispersive and counterpropagating on opposite edges of the 2D material [17,18]. A topologically nontrivial bulk gap opens at the Dirac points, and the above-mentioned flat edge band develops into the chiral subgap modes of a Chern insulator, where the latter are dispersive and counterpropagating on opposite edges of the 2D material [17,18] IV, we summarize our results and provide an outlook to our findings
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