Electrical Transport Properties and Spin Injection in $\hbox{Co}_{2}\hbox{FeAl}_{0.5}\hbox{Si}_{0.5}/\hbox{GaAs}$ Junctions

We investigated the electrical transport properties in Co
₂
FeAl
_0.5
Si
_0.5
(CFAS)/GaAs junctions. From current density-voltage characteristics, the formation of a Schottky tunnel barrier in the CFAS/GaAs interface was indicated. Moreover, junction resistance of 2×10
^-9
Ω·m
²
which is adequate for high magnetoresistance ratio attributable to high spin injection efficiency was obtained. Comparing the bias dependencies of conductance with samples, which CFAS ordering is lower, indicated that
L
2
₁
ordered CFAS contributes to electrical transport. Finally, the spin injection signal was observed with 3-terminal Hanle measurement, and spin relaxation time was estimated to be 380 ps at 5 K.