Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum-spin-Hall insulator with a large gap: single-layer 1T' WSe$_2$   Two-dimensional (2D) topological insulators (TIs) are promising platforms for
low-dissipation spintronic devices based on the quantum spin Hall (QSH) effect,
but experimental realization of such systems with a large band gap suitable for
room-temperature applications has proven difficult. Here, we report the
successful growth on bilayer graphene of a quasi-freestanding WSe$_2$ single
layer with the 1T' structure that does not exist in the bulk form of WSe$_2$.
Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling
microscopy/spectroscopy (STM/STS), we observed a gap of 129 meV in the 1T'
layer and an in-gap edge state located near the layer boundary. The system's 2D
TI characters are confirmed by first-principles calculations. The observed gap
diminishes with doping by Rb adsorption, ultimately leading to an
insulator-semimetal transition. The discovery of this large-gap 2D TI with a
tunable band gap opens up opportunities for developing advanced nanoscale
systems and quantum devices.

13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an