Study of the barrier height in exchange coupled Fe/Fe1-xSix (x > 0.70) multilayers

Fe/Fe1-xSix multilayers show distinct antiferromagnetic (AF) coupling for a wide spacer composition range 0.50 < x less than or equal to 1.00. As the Si content x increases, the spacer changes from metallic to insulating and the AF coupling strength (J) is significantly enhanced from 0.05 to 1.20 er g/cm(2). We have explained the temperature dependence of the coupling const ants J(1) and J(2) in terms of the quantum interference model by taking an unknown energy difference Delta(=U-epsilon(F)) as a fitting parameter, wher e epsilon(F) is the Fermi level of Fe and U is the potential of the Fe1-xSi x. The aim of the present work is to determine the quantity Delta experimen tally for the insulating composition range of x > 0.70. The quantity Delta was evaluated both from I-V characteristics and the temperature dependence of the resistivity with the current perpendicular to the sample plane using a crossed electrode geometry junction. It is found that the barrier height increases from 0.15 to 0.70 eV with increasing the Si content x. These val ues almost agree with the parameter Delta deduced from the temperature depe ndence of J(1) and J(2). This agreement supports the validity of our previo us calculations based on the quantum interference model. (C) 2000 American Institute of Physics. [S0021-8979(00)88708-3].