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Formation of nonmagneticc−Fe1−xSiin antiferromagnetically coupled epitaxial Fe/Si/Fe

“…It is now well established that a metallic iron silicide formed by Fe/Si interdiffusion is responsible for the interlayer coupling. [2][3][4][5][6][7][8][9] The exact composition of the iron silicides in the spacer layer is considered to be crucial to understanding the exponential decay of the AF coupling with the interlayer thickness 8 in the framework of the Anderson sd-mixing model 10 or the electron-optics model. 11 In several studies 2,7,9 it is suggested that Fe and Si form an FeSi alloy spacer layer with a metastable CsCl structure (c-FeSi) and an Fe:Si ratio close to 1.…”

FeSi diffusion barriers in Fe/FeSi/Si/FeSi/Fe multilayers and oscillatory antiferromagnetic exchange coupling

“…In figures 5(a) and (b) the area (relative intensity) of the subspectrum with the distribution P(B hf ) amounts to only 10% and 18%, respectively, of the total spectral area, providing only a weak contribution. The spectral parameters of the c-FeSi phase are δ = 0.26 mm s −1 and E Q = 0.15(1) mm s −1 , according to the literature [18,[33][34][35][36][37]. This metastable phase crystallizes in the B2 (or CsCl) structure with space group Pm 3m [33].…”

“…For x = 1 (nominally pure Si interlayers) the coupling strength is exponentially decaying, and for x = 0.5 (Fe 0.5 Si 0.5 interlayers) it exhibits an oscillating behavior and the overall coupling strength was reduced compared to the first case. Other groups also prepared epitaxial Fe/Fe 0.5 Si 0.5 /Fe sandwiches or multilayers which showed an exponential decrease of the EC with increasing Fe 0.5 Si 0.5 thickness [17][18][19][20], in contrast to [16] and [21]. Usually these discrepancies are ascribed to deviations in the stoichiometry of the interlayer and the smoothness of the interfaces which were claimed to be very good in [16,21].…”