All-electrical measurement of spin injection in a magnetic $p$-$n$   junction diode
  Magnetic $p$-$n$ junction diodes are fabricated to investigate spin-polarized electron transport. The injection of spin-polarized electrons in a semiconductor is achieved by driving a current from a ferromagnetic injector (Fe), into a bulk semiconductor ($n$-GaAs) via schottky contact. For detection, a diluted magnetic semiconductor ($p$-GaMnAs) layer is used. Clear magnetoresistance was observed only when a high forward bias was applied across the $p$-$n$ junction. 
Peifeng Chen, Juergen Moser, Philipp Kotissek, Janusz Sadowski, Marcus   Zenger, Dieter Weiss, Werner Wegscheider