Local electronic structure of Fe${}^{2+}$ impurities in MgO thin films: Temperature-dependent soft x-ray absorption spectroscopy study

Abstract

We report on the local electronic structure of Fe impurities in MgO thin films. Using soft x-ray absorption spectroscopy (XAS) we verified that the Fe impurities are all in the 2+ valence state. The fine details in the line shape of the Fe $L_{2,3}$ edges provide direct evidence for the presence of a dynamical Jahn-Teller distortion. We are able to determine the magnitude of the effective $D_{4h}$ crystal field energies. We also observed a strong temperature dependence in the spectra which we can attribute to the thermal population of low-lying excited states that are present due to the spin-orbit coupling in the Fe 3d. Using this Fe${}^{2+}$ impurity system as an example, we show that an accurate measurement of the orbital moment in Fe${}_3$O${}_4$ will provide a direct estimate for the effective local low-symmetry crystal fields on the Fe${}^{2+}$ sites, important for the theoretical modeling of the formation of orbital ordering.

References in corpus (4)

• Long Range Charge Ordering in Magnetite Below the Verwey Transition
• Charge and orbital order in Fe_3O_4
• Vanishing Fe 3d orbital moments in single-crystalline magnetite
• Direct observation of t2g orbital ordering in magnetite

Cited by in corpus (8)

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• Derivation of the spin Hamiltonians for Fe in MgO
• Negative charge transfer energy in correlated compounds
• Crystal structure and properties of iron-based spin-chain compound Ba9Fe3Se15
• Dynamic atomic reconstruction: how Fe3O4 thin films evade polar catastrophe for epitaxy