Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ion-beam modification of the magnetic properties of GaMnAs epilayers   We study the controlled introduction of defects in GaMnAs by irradiating the
samples with energetic ion beams, which modify the magnetic properties of the
DMS. Our study focuses on the low-carrier-density regime, starting with
as-grown GaMnAs films and decreasing even further the number of carriers,
through a sequence of irradiation doses. We did a systematic study of
magnetization as a function of temperature and of the irradiation ion dose. We
also performed in-situ room temperature resistivity measurements as a function
of the ion dose. We observe that both magnetic and transport properties of the
samples can be experimentally manipulated by controlling the ion-beam
parameters. For highly irradiated samples, the magnetic measurements indicate
the formation of magnetic clusters together with a transition to an insulating
state. The experimental data are compared with mean-field calculations for
magnetization. The independent control of disorder and carrier density in the
calculations allows further insight on the individual role of this two factors
in the ion-beam-induced modification of GaMnAs.

18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph