Figure 1

Schematic sample design with $\mathrm{Fe}/(\mathrm{Ga},\mathrm{Mn})\mathrm{As}$ contacts shown in red. The voltage is either measured in 3-T or nonlocal configuration. The inset shows a transmission electron micrograph of one of our $\mathrm{Au}/\mathrm{Fe}/(\mathrm{Ga},\mathrm{Mn})\mathrm{As}$ interfaces.Reuse & Permissions

Figure 2

(a) Electron micrograph of the central region of the device showing injector and detector stripes across the $50\mu \mathrm{m}$ wide GaAs channel. (b) Nonlocal voltage $V_{36}$ measured at $d=6\mu \mathrm{m}$ distance from the injector contact 2 for a reference sample without Fe on the 20 nm (Ga,Mn)As film at 50 K. The downward cusp at zero field is due to dynamical nuclear polarization (DNP). The sweep direction is given by arrows. (c) Major loops (top row, ${\mu }_{0}H$ between $\pm 200\mathrm{mT}$) and minor loops (bottom row, ${\mu }_{0}H$ between $+200\mathrm{mT}$ and $-18\mathrm{mT}$) of the 3-T and nonlocal signal for the $\mathrm{Fe}/20\mathrm{nm}$ (Ga,Mn)As sample at 50 K. Switching fields for Fe and (Ga,Mn)As (abbreviated by G) are marked by arrows. Within a minor loop the magnetization direction of (Ga,Mn)As switches (thick blue arrow) whereas the direction of the Fe magnetization remains unchanged (thick green arrow). The shift of the switching field due to exchange bias is indicated by the dashed vertical lines.Reuse & Permissions

Figure 3

Nonlocal signal $V_{36}$ for contacts with (a)–(d) and without (e)–(g) 2 nm Fe overlayer on 5 nm (Ga,Mn)As at different temperatures. (h) Signal height $\Delta V_{36}$ vs temperature for $\mathrm{Fe}/5\mathrm{nm}$ (Ga,Mn)As and its reference samples. Nonlocal Hanle signal (black squares) and corresponding fits (red line) after offset subtraction at 1.8 and 60 K for the $\mathrm{Fe}/5\mathrm{nm}$ (Ga,Mn)As device are presented in (i) and (j), respectively.Reuse & Permissions

Figure 4

(a) SQUID measurement of $m(H)$ for $\mathrm{Fe}/5\mathrm{nm}$ (Ga,Mn)As and the corresponding (Ga,Mn)As reference along [110] at 10 K. (b) $m(T)$ at a constant field of ${\mu }_{0}H=10\mathrm{mT}$ along [110]. $T_C$ of (Ga,Mn)As is taken at the inflection point of the measured $m(T)$ curves. The inset displays $\Delta T_C/T_C$ obtained from spin injection and SQUID data for different (Ga,Mn)As thickness $t$.Reuse & Permissions