Growth and magnetic oscillatory exchange coupling of Mn/Fe(001) and Fe/Mn/Fe(001)

The magnetic ordering and the interlayer exchange coupling in Mn and Fe/Mn wedge structures grown epitaxially on Fe(0 0 1) whisker substrates were inv estigated using scanning electron microscopy with polarization analysis (SE MPA). In bare Mn/Fe(0 0 1) samples, the magnetization of the top Mn layer i s collinear with the Fe magnetization, and oscillates between ferromagnetic and antiferromagnetic alignment as the Mn thickness increases. The period of the oscillation is two layers of Mn, consistent with the growth of an an tiferromagnetic Mn wedge. The bare Mn behaves very much like antiferromagne tic Cr, however the magnetic coupling in the Fe/Mn/Fe(0 0 1) sandwich struc tures is very different. For Mn thicknesses greater than four layers, the c oupling between the top Fe layer and the Fe whisker substrate is not collin ear. Between 4 to 8 layers of Mn, the direction of the top Fe in-plane magn etization lies at an angle of 60-80 degrees relative to the magnetization o f the Fe substrate. Beginning at the 9th Mn layer, the direction of the cou pling oscillates, with a two-layer period, between 90 degrees - phi and 90 degrees + phi, where phi is sample dependent. Values of phi between 10 and 30 degrees were observed. (C) 2000 Published by Elsevier Science B.V. All r ights reserved.