Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Suppression of magnetoresistance in thin $WTe_2$ flakes by surface
  oxidation   Recent renewed interest in layered transition metal dichalcogenides stems
from the exotic electronic phases predicted and observed in the single- and
few-layer limit. Realizing these electronic phases requires preserving the
desired transport properties down to a monolayer, which is challenging. Here,
using semimetallic $WTe_2$ that exhibits large magnetoresistance, we show that
surface oxidation and Fermi level pinning degrade the transport properties of
thin $WTe_2$ flakes significantly. With decreasing $WTe_2$ flake thickness, we
observe a dramatic suppression of the large magnetoresistance. This is
explained by fitting a two-band model to the transport data, which shows that
mobility of the electron and hole carriers decreases significantly for thin
flakes. The microscopic origin of this mobility decrease is attributed to a ~ 2
nm-thick amorphous surface oxide layer that introduces disorder. The oxide
layer also shifts the Fermi level by ~ 300 meV at the $WTe_2$ surface. However,
band bending due to this Fermi level shift is not the dominant cause for the
suppression of magnetoresistance as the electron and hole carrier densities are
balanced down to ~ 13 nm based on the two-band model. Our study highlights the
critical need to investigate often unanticipated and sometimes unavoidable
extrinsic surface effects on the transport properties of layered
dichalcogenides and other 2D materials.

9
The categories of this paper are: nlin
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci