Planar Hall effect measurements were carried out on two GaMnAs ferromagnetic films with different Mn concentrations (6.2 and 8.3 Mn). The switching fields of magnetization taken from field scans of the planar Hall effect showed significantly different angular dependences in the two samples. While the angular dependence of the switching field for the sample with 8.3 Mn had a symmetric rectangular shape in the polar plot, that of the other sample with 6.2 Mn exhibited a clearly asymmetric behavior, with large steps at the 110 crystallographic directions. This switching field behavior was analyzed by considering pinning fields for crossing the 110 directions. The fitting of step features appearing at the 110 directions revealed the presence of a new uniaxial anisotropy field Hu2 along the 100 direction, in addition to the commonly observed cubic Hc anisotropy field (along the 100 directions) and uniaxial anisotropy Hu1 fields (along either the 110 or the [1 1 0] direction) in the GaMnAs film.
Bibliographical noteFunding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science and Technology (No. 2010-0015952); by Mid-career Researcher Program through NRF grant funded by the Ministry of Education, Science and Technology (No. 2009-00852028), and (No. 2010-0000123), and by the National Science Foundation Grant DMR10-05851.
ASJC Scopus subject areas
- General Physics and Astronomy