Figure 4: Measurement results of the magnetization-direction dependence of the tunnel transport in devices A–C.

(a,d,g) Colour-coded maps representing the normalized dI/dV as a function of the magnetic field direction
and V. The normalized dI/dV is defined by equation (1). The negative voltage region in device A is classified into three parts X, Y and Z by the sign of the oscillation in the normalized dI/dV-
curves. (b,e,h) Characteristics of dI/dV-V at
=0°. The blue and green arrows indicate V corresponding to the peak and dip, respectively, that are used in c,f,i. The blue and pink regions shown on the right side represent the valence band (VB) and impurity band (IB) regions in GaMnAs, respectively. The red dash-dotted lines represent the Fermi level EF (V=0). (c,f,i) The normalized dI/dV-
curves at V corresponding to the positions of the blue and green arrows in b,e,h, respectively. The black solid curves are the fitting curves expressed by equation (2).