Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pressure induced evolution of band structure in black phosphorus studied
  by $^{31}$P-NMR   Two-dimensional layered semiconductor black phosphorus (BP), a promising
pressure induced Dirac system as predicted by band structure calculations, has
been studied by $^{31}$P-nuclear magnetic resonance. Band calculations have
been also carried out to estimate the density of states $D(E)$. The temperature
and pressure dependences of nuclear spin lattice relaxation rate $1/T_1$ in the
semiconducting phase are well reproduced using the derived $D(E)$, and the
resultant pressure dependence of semiconducting gap is in good accordance with
previous reports, giving a good confirmation that the band calculation on BP is
fairly reliable. The present analysis of $1/T_1$ data with the complemental
theoretical calculations allows us to extract essential information, such as
the pressure dependences of $D(E)$ and chemical potential, as well as to
decompose observed $1/T_1$ into intrinsic and extrinsic contributions. An
abrupt increase in $1/T_1$ at 1.63GPa indicates that the semiconducting gap
closes, resulting in an enhancement of conductivity.

33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics