text: Similar behavior is observed for bilayer samples con- 
  taining a 10 nm or 50 nm (Ga,Mn)As layer, with a 
  bias ﬁeld which is approximately inversely proportional 
  to the thickness d of the ferromagnetic semiconductor 
  layer (Fig. 1, inset). This 1/d dependence of HE was 
  found previously for MnAs/(Ga,Mn)As bilayers4, and 
  is generally observed in exchanged-biased thin ﬁlms12. 
  From this dependence it is possible to describe the ex- 
  change bias in terms of an interface energy per unit area, 
  ∆E = MF SHEd = 0.003 erg/cm2. This value is rather 
  small compared to typical exchange bias systems12, re- 
  ﬂecting the low moment density MF S of the diluted 
  FM semiconductor layer. However, the bias ﬁeld for a 
  given (Ga,Mn)As thickness is larger than is observed for 
  MnO/(Ga,Mn)As structures13, while the reproducibility 
  and ﬂexibility of the present structures is much higher 
  due to the single-crystalline ferromagnetic nature of the 
  Fe layer. 