Magnetic microscopy of Fe/Mn/Fe layers

摘要

Manganese layers were deposited on polycrystalline Fe-based soft magnetic films.The magnetic domain structure of thin Fe overlayers on top these Mn films was measured by secondary electron microscopy with polarization analysis. The Fe layers show spin polarization only beyond a cartain critical thickness of about 20 A.Beyond this thickness the domain structure of the substrate strts to appear in the Fe overlayer.This delayed onset of ferromagnetic order in the Fe layers is attributed to frustration of ferromagnetic order due to the strong coupling to the antiferromagnetically ordered Mn. With increasing Fe film thickness (between 20-30 A) the magnetization increases and shows the same domain patternas the substrate.We find that for all Mn thicknesses studied (up to 170 A) the Fe overlayer domain structure reproduces the substrate domain structure and the magnetization is always aligned parallel with the substrate magnetization.