Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Design triple points, nexus points and related topological phases by
  stacking monolayers   Triple points and nexus points are two interesting topological phases, which
have been reported in some three-dimensional (3D) materials. Here, we propose
that triple points, nexus points and related phases, such as topological tangle
nodal lines, can be obtained by alternatively stacking two types of monolayers.
Two conditions for the stacking monolayers are required: the first condition is
that they have a three-fold (C3) rotation symmetry and three mirror planes
along the C3 axis; the second condition is that one of the monolayers should be
insulating while the other one should be metallic (or semiconducting) and has a
double degenerate band and a nondegenerate band at {\Gamma}point around the
Fermi level. Hexagonal boron nitride (HBN) and {\alpha}/{\alpha}^'-boron sheets
({\alpha}/{\alpha}^'-BS) are suggested as candidate materials. Even if HBN is a
wide-gap insulator, the interactions between layers lead to crossings of the
nondegenerate and double degenerate bands along the direction normal to the
nanosheets, and thus form triple/nexus points or related phases. A
tight-binding model is adopted to explain the phase transition between triple
points, nexus points and other related phases.

14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph