Cation- and lattice-site-selective magnetic depth profiles of ultrathin $\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4$(001) films

Abstract

A detailed understanding of ultrathin film surface properties is crucial for the proper interpretation of spectroscopic, catalytic and spin-transport data. We present x-ray magnetic circular dichroism (XMCD) and x-ray resonant magnetic reflectivity (XRMR) measurements on ultrathin $\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4$ films to obtain magnetic depth profiles for the three resonant energies corresponding to the different cation species $\mathrm{F}{\mathrm{e}}_{\mathrm{oct}}^{2+}$, $\mathrm{F}{\mathrm{e}}_{\mathrm{tet}}^{3+}$ and $\mathrm{F}{\mathrm{e}}_{\mathrm{oct}}^{3+}$ located on octahedral and tetrahedral sites of the inverse spinel structure of $\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4$. By analyzing the XMCD spectrum of $\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4$ using multiplet calculations, the resonance energy of each cation species can be isolated. Performing XRMR on these three resonant energies yields magnetic depth profiles that correspond each to one specific cation species. The depth profiles of both kinds of $\mathrm{F}{\mathrm{e}}^{3+}$ cations reveal a $3.9\pm 1\mathring{\mathrm{A}}$-thick surface layer of enhanced magnetization, which is likely due to an excess of these ions at the expense of the $\mathrm{F}{\mathrm{e}}_{\mathrm{oct}}^{2+}$ species in the surface region. The magnetically enhanced $\mathrm{F}{\mathrm{e}}_{\mathrm{tet}}^{3+}$ layer is additionally shifted about $3\pm 1.5\mathring{\mathrm{A}}$ farther from the surface than the $\mathrm{F}{\mathrm{e}}_{\mathrm{oct}}^{3+}$ layer.

5 pages, 3 figures, supplemental pdf

References in corpus (10)

• Iron Oxide Surfaces
• Subsurface Cation Vacancy Stabilization of the Magnetite (001) Surface
• Observation of the spin Seebeck effect in epitaxial Fe3O4 thin films
• Static magnetic proximity effect in Pt/NiFe2O4 and Pt/Fe bilayers investigated by x-ray resonant magnetic reflectivity
• Static magnetic proximity effect in Pt/Ni${}_{1-x}$Fe${}_x$ bilayers investigated by x-ray resonant magnetic reflectivity
• Temperature-Dependence of Magnetically-Active Charge Excitations in Magnetite across the Verwey Transition
• From Fe${}_3$O${}_4$/NiO bilayers to NiFe${}_2$O${}_4$-like thin films through Ni interdiffusion
• Sign change in the tunnel magnetoresistance of Fe3O4/MgO/Co-Fe-B magnetic tunnel junctions depending on the annealing temperature and the interface treatment
• Electronic and magnetic structure of epitaxial NiO/Fe${}_3$O${}_4$(001) heterostructures grown on MgO(001) and Nb-doped SrTiO${}_3$(001)
• Advanced data analysis procedure for hard x-ray resonant magnetic reflectivity discussed for Pt thin film samples of various complexity

Cited by in corpus (2)

• Spin- and time-resolved photoelectron spectroscopy and diffraction studies using time-of-flight momentum microscopes
• Structural and magnetic investigation of the interfaces of $\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4/MgO(001)$ with and without NiO interlayer