Electron energy-loss magnetic chiral dichroism of magnetic iron film affected by an underlayer in a double-layer structure

X. Fu, K. Wu, V. Serin, B. Warot-Fonrose, Q. He, R. Yang, L. Zhang, X. Huang
2019 Applied Physics Letters  
Fonrose, Q. He, et al.. Electron energy-loss magnetic chiral dichroism of magnetic iron film affected by an underlayer in a double-layer structure. ABSTRACT The electron energy-loss magnetic chiral dichroism (EMCD) technique has been generally applied to single-phase magnetic crystals while rarely used for composite structures. It is mainly due to the lack of in-depth understanding of EMCD in the latter case where an additional phase may present under or above the investigated magnetic phase in
more » ... d magnetic phase in the electron beam path. Here, we report EMCD signals acquired on a 15-nm-thick magnetic iron film with different thicknesses of the MgO substrate underlayer. By comparison, for areas with total thicknesses of t ¼ 0:59k and t ¼ 1:02k expressed with the mean free inelastic path of electron k, the relative dichroic signals at the Fe-L 3 edge are 3:8%61:0% and 3:5%61:6%, respectively, demonstrating no significant difference within the error range. However, the dichroic signal intensity at the Fe-L 2 edge peak is 77.6% larger in the thinner area of t ¼ 0:59k. Accordingly, the extracted m L =m s ratio of Fe 3d moments is 63% smaller in the thinner area even after the plural scattering is removed. Then, we confirm that the presence of an additional nonmagnetic phase under a magnetic iron crystal can noticeably affect the quantified value of the m L =m s ratio of iron moment determined from the EMCD measurements. Furthermore, the larger thickness of the underlayer may result in relatively higher valuation of the m L =m s ratio of the upper layer. A correction method, considering the different influence of the underlayer on the Fe-L 3 and L 2 edges, is in demand for developing potential applications of the EMCD technique to such composite nanomaterial systems. Published under license by AIP Publishing. https://doi.
doi:10.1063/1.5100245 fatcat:p7e3ip6hmjg4dcre4n2skbltvi