Role of interfaces in the exchange coupling of Fe/Cr/Fe(001) systems

Exchange coupling has been studied in Fe whisker/Cr/Fe(001) systems that were grown in a perfect layer by layer mode. The exchange coupling through Cr was found to be very sensitive to alloying at the Fe whisker/Cr(00l) interface. It will be shown that the observed reversed phase of the short wavelength oscillations compared to those predicted by ab initio calculations can be caused by alloying at the Fe whisker/Cr(001) interface. In order to test this point, we have grown samples with the Cr/Fe(001) interface intentionally alloyed by codepositing the Cr and Fe atoms during the formation of the last Cr atomic layer. The strength of the exchange coupling has also been investigated in systems fabricated with heterogeneous spacers using bcc Cu(001) and fee Ag(001). Cu and Ag layers have been inserted between the Cr spacer and the Fe(001) film. The strength of the antiferromagnetic coupling was found to be substantially increased due to the presence of Cu at the Cr/Fe(001) interface. It will be argued that the observed increase in the exchange coupling is caused by an increased asymmetry in spin dependent reflectivity at the Cr/Cu/Fe interface. (C) 1997 American Institute of Physics.