Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Influence of the velocity barrier on the massive Dirac electron
  transport in a monolayer MoS$_{2}$ quantum structure   Using the transfer matrix method, spin- and valley-dependent electron
transport properties modulated by the velocity barrier were studied in the
normal/ferromagnetic/normal monolayer MoS$_{2}$ quantum structure. Based on
Snell's Law in optics, we define the velocity barrier as $\xi=v_{2}/v_{1}$ by
changing the Fermi velocity of the intermediate ferromagnetic region to obtain
a deflection condition during the electron transport process in the structure.
The results show that both the magnitude and the direction of spin- and
valley-dependent electron polarization can be regulated by the velocity
barrier. $-100\%$ polarization of spin- and valley-dependent electron can be
achieved for $\xi>1$, while $100\%$ polarization can be obtained for $\xi<1$.
Furthermore, it is determined that perfect spin and valley transport always
occur at a large incident angle. In addition, the spin- and valley-dependent
electron transport considerably depends on the length $k_{F}L$ and the gate
voltage $U(x)$ of the intermediate ferromagnetic region. These findings provide
an effective method for designing novel spin and valley electronic devices.

13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: econ