Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Klein Tunneling and Berry Phase $\pi$ in Bilayer Graphene with a Band
  Gap   Klein tunneling in gapless bilayer graphene, perfect reflection of electrons
injecting normal to a pn junction, is expected to disappear in the presence of
energy band gap induced by external gates. We theoretically show that the Klein
effect still exists in gapped bilayer graphene, provided that the gaps in the n
and p regions are balanced such that the polarization of electron pseudospin
has the same normal component to the bilayer plane in the regions. We attribute
the Klein effect to Berry phase $\pi$ (rather than the conventional value $2
\pi$ of bilayer graphene) and to electron-hole and time-reversal symmetries.
The Klein effect and the Berry phase $\pi$ can be identified in an electronic
Veselago lens, an important component of graphene-based electron optics.

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The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics