Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: van der Waals metamaterials   The van der Waals heterostructures are a fertile frontier for discovering
emergent phenomena in condensed matter systems. They are constructed by
stacking elements of a large library of two-dimensional materials, which couple
together through van der Waals interactions. However, the number of possible
combinations within this library is staggering, and fully exploring their
potential is a daunting task. Here we introduce van der Waals metamaterials to
rapidly prototype and screen their quantum counterparts. These layered
metamaterials are designed to reshape the flow of ultrasound to mimic electron
motion. In particular, we show how to construct analogues of all stacking
configurations of bilayer and trilayer graphene through the use of interlayer
membranes that emulate van der Waals interactions. By changing the membrane's
density and thickness, we reach coupling regimes far beyond that of
conventional graphene. We anticipate that van der Waals metamaterials will
explore, extend, and inform future electronic devices. Equally, they allow the
transfer of useful electronic behavior to acoustic systems, such as flat bands
in magic-angle twisted bilayer graphene, which may aid the development of
super-resolution ultrasound imagers.

34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph