Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin Hall effect in two-dimensional $p$-type semiconductors in a
  magnetic field   We calculate the spin Hall conductivity driven by Rashba spin-orbit
interaction in $p$-type two-dimensional semiconductors in the presence of a
perpendicular magnetic field. For a highly confined quantum well, the system is
described by a $k$-cubic Rashba term for two-dimensional heavy holes.
  The eigenstates of the system can be described by
  Landau spinor states. First we consider the conventional spin Hall
conductivity. The contribution of the interband transitions to the
Kubo-Greenwood formula gives the density dependent intrinsic spin Hall
conductivity, which approaches its universal value $\sigma^z_{xy}=9e/8\pi$ for
weak spin-orbit coupling and low Fermi energies, in agreement with previous
work.
  However two intraband contribution terms cancel this effect leading to zero
conventional spin Hall conductivity. Adding the torque dipole contribution to
the definition of spin current, we also study the {\it effective} spin
conductivity. This is shown to be proportional to the total magnetization plus
surface terms which exactly cancel it for small spin-orbit coupling. If in low
magnetic field the intraband transitions evolve to vertex corrections, the fact
that both {effective} and conventional spin Hall conductivities vanish is
unexpected. This suggests that the zero magnetic field limit of the model is
singular.

13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th