Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hexagonal warping on spin texture, Hall conductivity and circular
  dichroism of Topological Insulator   The topological protected electronic states on the surface of a topological
insulator can progressively change their Fermi cross-section from circular to a
snowflake shape as the chemical potential is increased above the Dirac point
because of an hexagonal warping term in the Hamiltonian. Another effect of
warping is to change the spin texture which exists when a finite gap is
included by magnetic doping, although the in-plane spin component remains
locked perpendicular to momentum. It also changes the orbital magnetic moment,
the matrix element for optical absorption and the circular dichroism. We find
that the Fermi surface average of z-component of spin is closely related to the
value of the Berry phase. This holds even when the Hamiltonian includes a
subdominant non-relativistic quadratic in momentum term (which provides
particle-hole asymmetry) in addition to the dominant relativistic Dirac term.
There is also a qualitative correlation between $\left\langle S_z
\right\rangle$ and the dichroism. For the case when the chemical potential
falls inside the gap between valence and conduction band, the Hall conductivity
remains quantized and unaffected in value by the hexagonal warping term.

36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol