We have carried out the planar Hall effect measurement on two different sizes of Hall bar devices fabricated from GaMnAs ferromagnetic films. The detailed information on the magnetic anisotropy properties including the shape anisotropy field were obtained from the angular dependence of planar Hall resistance. The shape anisotropy field per magnetization in the device with 10 μm channel width was about 39 G. Though the value of shape anisotropy is small, it affects the magnetization reversal processes of the 10 μm Hall device by showing steplike feature in the angular dependence of switching fields.
Bibliographical noteFunding Information:
This work was supported by Korea Research Foundation Grant No. KRF-2004-005-C00068, by the Seoul R&DB Program, and by the National Science Foundation Grant No. DMR06-03762. FIG. 1. Schematic diagram for the Hall device along with crystallographic directions. FIG. 2. Planar Hall resistance (PHR) data taken at four different applied field angles of φ H = 5 ° , 35°, 90°, and 145° for the 300 μ m (left column) and the 10 μ m (right column) Hall devices. The detailed changes of PHR near the zero field are given in the inset of the second and fourth rows. FIG. 3. Angular dependence of switching fields for the 300 and 10 μ m GaMnAs Hall devices. The steps appear at the hard axis angles in the switching field from the 10 μ m device. FIG. 4. The relation between the direction of magnetization and the external field direction obtained from PHR data. The solid lines are the fitting results using Eq. (2) .
ASJC Scopus subject areas
- Physics and Astronomy(all)