Figure 1

Angular dependences of PHR data taken at several magnetic fields for as-grown (left column) and annealed (right column) GaMnAs films. The open and solid symbols show data taken with field rotations in CW and CCW directions, respectively. Note the striking hysteresis between the CW and CCW rotations observed at lower field values.Reuse & Permissions

Figure 2

(Color online) Probability of finding magnetic domains oriented along the [010] direction for a given pinning field. The widths of the distributions show clear contrast between as-grown (solid circles) and annealed (open circles) GaMnAs. The solid lines are Gaussian fits obtained with Eq. (4). The left-hand inset shows the fractional area $p$ corresponding to magnetic domains with magnetization along [010] obtained from data in the shaded region of Fig. 1. The right-hand insets are plots of the relation between $p$ and the pinning field $\Delta E/M$ mapped out from the data shown in the left inset.Reuse & Permissions

Figure 3

(Color online) Representative field scans of PHR data obtained on as-grown (upper panel) and annealed (lower panel) GaMnAs films for field directions ${\phi }_H=105°$ and ${\phi }_H=135°$. Both scans of the annealed film show significant changes near zero field, giving the same intermediate value at the intercept. The zero-field intercepts obtained for PHR scans for the annealed film at different ${\phi }_H$ are given in the left-hand inset, showing that the transition occurs between two PHR values that correspond to a combination of two directions of magnetization, $\phantom{\Vert }\mathbf{M}\Vert \left[100\right]$ and $\phantom{\Vert }\mathbf{M}\Vert \left[010\right]$. This is illustrated in the right-hand inset where $M_U$ and $M_C$ indicate magnetizations dominated by uniaxial and cubic anisotropies, respectively. The dotted lines in the left inset indicate the filed angles, at which the representative field scans of PHR data are obtained.Reuse & Permissions

Figure 4

(Color online) Magnetic field dependence of the maximum-to-minimum amplitude of PHR obtained from the angular dependence data. The solid and open circles correspond to as-grown and annealed samples. Note the striking difference between the behavior of the two materials at fields below 40 Oe (i.e., below saturation of M). The schematic of the Hall device used in the PHR measurements, together with crystallographic direction, is shown in the inset.Reuse & Permissions